There are missing pieces & parts that have been corroded into a no longer quite functional position now.
- Players(and monsters) are no longer sticky so can just walk right up to the prime target with few if any consequences & little of value that can be done. There is no longer any meaningful reason to look at the battlefield & coordinate with others on how to approach or what to approach.
Well I think this is blatantly false... there is the possible consequence of opportunity attacks due to movement, terrain hinderances, ranged attacks, AoE attacks and so on. The meaningful reason to look at the battlefield and coordinate is (as it has always been) to minimize total damage taken and maximize opponents being taken out.
- The buff/debuff/control spells you note are almost universally concentration so casting a buff on someone who is "good at combat" means the caster cant also cast debuff & control spells resulting in a net loss or resource expenditure that does little to nothing. As a wizard who gravitates to spells like web & slow why they don't cast haste... he could & the barbarian or whatever would get an extra attack because of what should be a great spell... but it comes at the cost of slow & web. For that note ask why he never casts slow on the big bad while he's got web on the mooks.
I'm not sure we are looking at this in the same way as this seems to be an assertion that supports my position. Does the caster upon affecting creatures with slow rush in and dispatch them... or does he instead coordinate with the fighter to attack the creatures he has debuffed?? In other words Slow and Web when used with teamwork work better, they make the fighter more effective against said enemies while the caster rushing in to fight them solo is sub-optimal at best.
- The control/buff/debuff abilities that do exist tend to be crippled with pointless & almost petty strings like free no action cost save to end/ignore every round and concentration... Those same saves and a short duration... A pointlessly long duration & no ability to move the spell to another monster/the next fight plus concentration & maybe even a free save every round.
thus creating a situation where it is best to coordinate in taking those monsters out as quickly as possible... teamwork.
- Nobody really looks or feels squishy anymore. This is partly monster design & partly the design of PCs themselves. There's not really any need for the crunchy types to protect or even consider the squishies any more
Huh?? This hasn't been my experience at all... The casters (with exception of some druids and clerics) are pretty squishy unless they are expending resources that could actually optimize their party in combat on their own personal protection. I'm not seeing wizards, bards, sorcerers rushing into melee combat, I'm seeing them keep their distance and help the frontline fighters end the fights as quickly as possible.
Here are some examples:
- An ogre might be the biggest threat sure, but if all of the crunchy types ignoring the five goblins to focus fire means the casters will be ganked when there is nobody in the way to create a sticky zone of control by being there the controller is going to be running for his life instead of controlling the bottlenecked cluster of goblins now close enough to each other to get a good chunk in the web. Now the controller might more 30ft to not risk concentration sure, but he's never really at risk & to be honest it doesn't really matter if web breaks after a couple rounds.
I'm not understanding this example... so there is risk that the controller, without teamwork and positioning will be ganked, but he's never really at risk??
- The party's really not comfortable with being close to the ogre at this level yet. No big deal drop web & cast ray of enfeeblement so the 5 goblins can gank the squishies as concentration moves oops.
What squishies... you claimed no one was really squishy anymore in 5e. Also, what is a concentration move? And who are the spells being cast upon and aren't these both concentration spells??
- A second ogre or a few more goblins arrives just um.. run.. yea run or maybe soak up a ton of healing word/healing light from the bard/cleric/druid/celestial warlock whatev' no need to pull out all the stops.
Having to cast all the spells you are assuming this party has access too, without having actually killed anything, honestly seems to be pulling out all the stops for one encounter.
Th party can't stack force multipliers upon force multipliers because they can pretty much never use more than one at a time & they as characters can't really do anything more than "focus fire" when the unexpected or unsafe happens
What does whether they can stack multiple force multipliers have to do with whether teamwork would help an encounter or not. And teamwork can involve positioning, strategy on what enemies to cast spells upon and subsequently attack, what maneuvers should be used for a BM fighter and so on. You're definition of teamwork either seems very limited or narrowly specific, I'm honestly not sure yet which it is, or maybe I just don't understand your above examples...