Oh, and while on the subject 4e was never a strategic game. Out of character strategy was vastly reduced from 3.X; character optimisation was still a big thing but the object of character optimisation was seldom to create the next Pun-Pun or otherwise snap the game across your knee in character creation so much as get an edge and to make characters work in ways the designers hadn't thought of. And in character once again 3.X was the example of a strategic game, where you won in spell preparation and spell selection.
Of similar importance:
personal optimization was almost always less important than
team optimization. That is: ruthlessly optimizing your own numbers and action economy was likely to do poorly, while ruthlessly optimizing
the team's numbers and action economy was likely to produce stunning success. This is exactly the opposite of 3e, where I have been explicitly told by multiple optimizers that it is absolutely a game about highly optimizing your own stuff, and any team dynamics that result are an emergent perk, not a design goal. 5e appears to have gone back to that side of things, albeit slightly more reservedly since "ruthless optimization" doesn't
earn as much as it did back in 3e.
This is a seriously under-appreciated Big Issue with 3e. D&D is, and for quite some time has consistently been, a cooperative game. Yes, you can
make a competitive game out of it, but that's very clearly not what it's designed for. Character classes are given weak points that are partly or completely compensated for by the strengths of other classes; even people who dunked on 4e's explicit class roles admitted that D&D had implicit class roles all the way back at the beginning. The game's design is implicitly cooperative, but (prior to 4e) it really did almost nothing to encourage actually
behaving cooperatively. In-combat healing (outside of 4e) is almost always less efficient than just doing damage; a dead monster has 100% of its damage mitigated, and (prior to 4e) out-of-combat healing was best done through resources rather than spells. In-combat buffing (outside of 4e) is usually less efficient than battlefield control/save-or-suck/save-or-lose/save-or-die, and out-of-combat buffing (even in 4e) rarely lasts long enough to matter for the next combat (unless you're doing scry-and-fry, which is its own ball of wax).
These are all reasons why 4e fans didn't take it well when a bunch of straightforward 4e mechanics (like minor actions, at-wills, bloodied) got a kludgy or half-baked remake in 5e ("bonus actions," cantrips, literally doing the same thing but dancing around it without a name). These things didn't exist just to exist; they all served clear, identifiable
functions, and specifically did so to foster a
team-centric approach to play. Minor-action healing existed to make support characters more enjoyable, because you could provide support
and do your Special Things, but then 5e took that away (can't cast a Bonus Action spell and a regular Action spell in the same turn unless the latter is a cantrip). At-wills existed to give you solid fallback options
with meaningful effects when you didn't want to (or weren't sure whether to) deploy the big guns, but 5e took that away (only casters get cantrips, the "cantrip" for a 5e non-caster is...making more attacks, or maybe shoving
instead of doing damage rather than
on top of doing damage.) Bloodied...well, I mean, they literally just kept the mechanic but pretended it wasn't related by dropping the name, so I guess that's a clear "5e kept it." But seriously, dancing around it without
naming it is clearly "we can't LOOK like 4e even if we're USING 4e," which isn't going to endear 5e to someone who liked 4e.
Edit: It's worth noting, 4e's specific way of achieving "support party-based play and reasoning" is NOT the only way to do it. (I know you know this, Neonchameleon, but I think you can guess this post is more using yours as a jumping-off point rather than talking to you personally). The problem, for many 4e fans, is that 5e didn't seem to
care about "support party-based play and reasoning," instead, as noted, going back to the 3e "optimize yourself, that's the best possible contribution you can make" mentality. The problem isn't "5e did something different, so it sucks"; instead, it's "5e didn't get the
point of the mechanics, so it kept things (seemingly) without keeping their purpose and dropped things (seemingly) without knowing why they were present."
What 4e was was a tactical game where you won by engaging with the shared fiction. You used forced movement to push the enemies into aspects of the game world, making it something that was very present rather than the environment of the fight being effectively present rather than areas on the floor marked out for people to step round as they act against a green screen. You used reactions and interrupts to respond to what the enemy was doing and prevent them doing what they wanted while persuading them to do what you want. It's not the strategic game which is to hit the right save-or-suck spell or to keep hitting until the enemy hp gauge hits zero. It's to engage with the gameworld and what the other side is doing.
And that people think that engaging with the world and the actions of the other side somehow makes for less of a story than doing what you do in near isolation and forcing the abstract number of the hp gauge down with limited incorporation of what they are doing or where they are to me says a lot about their taste in stories.
You see similar things in other 4e mechanics as well. My poster-child example for this is the Lay on Hands mechanic, because it's existed in (AFAIK) every edition of D&D, but
only 4e made it one where the mechanics ARE the story and the story IS the mechanic.
In every other edition of D&D, including Pathfinder, Lay on Hands is just a bonus pool of points you can spend. It's a special healing bank account that your deity refills once a day. Honestly, pretty boring, but since it was all I knew for a long time, I liked it.
Then 4e comes along and says, "We can do better." In 4e, for those unfamiliar, Lay on Hands is a daily power that can be used more than once (specifically, Wis mod times per day, but only once per round), on an adjacent ally (you have to be able to touch them!) When used, the
Paladin spends one Healing Surge, but the
target heals as if
they had spent one. It is, very literally, "I give of myself, to replenish you." That's insanely flavorful! The Paladin is literally sacrificing some of her own (enhanced) vitality in order to heal others. And you can make it better--you can invest resources to let it do other things, or to use your surge value rather than the target's (being a defender, you usually have more HP, so this is a good deal), or give extra healing if used on other people (because you
can use it on yourself).
THAT is the kind of thing 4e mechanics strive for. Not everything succeeds at doing so. But the core idea is there, and it succeeds more often than it fails: the mechanics don't just imply a story, they
are the story.