True, but that is why ACs don't climb fast. Seemed to me the game was set up so most critters are a legitimate threat for some time in modest sized groups. Sure the band of bandits don't matter so much after a few levels, but they can still plink the PCs while allied half ogres tear them up and having send the fireballs at said bandits to keep them from pincushioning soft targets creates tactical considerations.
It is set up this way, but there is still a lack of NPCs and hero type monsters at higher levels. You can't just throw endless waves of lower CR creatures at your group.
Also there is the consequence of having too many creatures slows down combat quite a bit, and also it's not practical in some circumstances. For example, right now my group is exploring a tower. I simply can't fit 5 creatures into a room.
How many high level casters do you plan for the players to fight. Those types generally are not common unless one frees / summons a bunch from the underworld. Also a handful of lower level casters and a couple mid power mages might be better foe group rather than a single higher level caster doomed to being outgunned in the action economy.
I'm running City of the Spider Queen, which is D&D Forgotten Realms Cannon. There are a lot of casters. There's actually 42 pages of stat blocks to convert (which I have almost finished, after 8 months now). But do note that the majority of classes in D&D are casters, even Fighters are "casters" in a sense that unless you just want them to be a boring bag of hit points at CR16, you actually need to give them something cool to do, like legendary actions. All this takes time.
Low level casters taken straight out of the Monsters Manual will basically die the first round. They're not constructed very well, far too low defensive CR.
Believe me, I've gone through all this.
But i'll agree, CRing an NPC can be a bit fiddly because the system has a modest bit of precision.
Edit: There is a bunch of new NPC foes in the Princes of the Apocalypse. Many are heavily elemental themed, but still a decent mix.
Now this last bit is the nail on the head. Back in 3rd edition you built a class from the PHB and it's EL was that + 1. 5e its WAY different and much more accurate. However, the way the game plays it's not really a good idea to build PHB classes and use them as monsters for various reasons (lack of HP, lack of buffs, concentration, etc), which adds time, complexity, but it does add accuracy.
If you don't care about providing a challenge to your players, and/or don't use XP and just like to wing things, sure, 5e can be pretty fast to "convert" at the higher levels. Although I don't really consider that converting a module, that's more just winging it.
I'll give you an example. City of the Spider Queen uses lots of vampires and undead. Let's look at the Vampire example first.
They have a range of Drow and Drider vampires that range from named NPCs to rank and file warriors. In 5e you have the option of using the legendary vampires and CR5 vampire spawn. That's it.
Useless endless ranks of CR5 vampire spawns would be mind numbingly boring for my players, and also pretty easy for them to take out (they are level 16 now). Even the CR13 "legendary" Vampires are basically dead in 1 or 2 rounds now to them. So how would you propose I set up a BBEG fight that the module calls for hmm? You actually have to roll up your sleeves and make something using the DMG rules. All this takes time.
Another example is they're fighting a lot of revenants who have different flavours. Some are Fighter types, some are Wizard types, and some are Fighter/Wizard types with an anti-caster flavour. Using endless ranks of CR5 revenants from the MM again would become mind numbingly boring for my group, and also would lose a lot of the original modules flair of having these intermingled groups who provide layers of tactical defense to each other.
So one encounter - EL17 - you have a Drow Cult Champion (meant to be a tough Drow Fighter/Cleric), four Revenant Officers, one Ethereal creature (which I substituted with the ghost straight from the MM). Then in the next room, which a very high chance of joining the fight, you have Four Revenant Shattered Tower Guards, which are meant to be Fighter/Wizards.
How are you going to whip that up in 15 minutes?
- First of all, there's nothing in the MM that will give you an interesting encounter that's meant to challenge by 16th level group using nothing but hoards of CR1-5 creatures.
- Second of all, using large hoards of low level CR things slows down combat too much, and just won't fit on the map.
- Thirdly, you have to keep the flavour of the original encounter. Having a Cult Champion that dies in one shot (or doesn't stand up to the party in a challenging way) won't really work very well in terms of the flavour of the module, so she has to be *at least* CR10.
- Fourhtly, then you have to fiddle around with numbers and CRs, because numbers of creatures in 3rd edition are handled completely different from number of creatures in 5th edition. But what I am finding is that the numbers multiplier in the DMG doesn't really work *at all* when creatures are more than 5 or so CR below the party level. x2-x3 for encounter difficulty when you have say a CR12, 3xCR8, and 1xCR4 is quite frankly wrong against a party with the resource level that a level 16 group has. So you've got to basically just throw all that away anyway and do it by feel, which only comes with experience.
So again - at the higher levels when converting a module - it's not quite as simply as pulling out the MM, tweaking a couple of things, and away you go. It's tedious work.
Then there is also added work if you are using digital tools, and using a lot of older stuff, that you basically don't have any maps and have to make them yourself.
Using the back catalog to support D&D moving forward is putting a huge amount of work in the arms of DMs, especially given the
faster level advancement now as well.
I'm very much looking forward to running pure 5e stuff when I have finished this campaign.