Pacing is important to the game (or at least the threat of pacing, but that's tangential). If you allow the party a long rest after every encounter, for example, you have much bigger issues than Simulacrum, at much earlier levels than the spell is available.
IMO, a pacing issue is a pacing issue, not an issue specific to Simulacrum.
The problem is that it adds a new pacing issue that is unique to longer lasting spells like simulacrum and contingency. With the 6-8 encounter thing...you don't actually need to do 6-8 encounters every single day. You can have days that are busy in terms of combat, and then days of travel or investigating in a city or trying to get something political done. You can have your attrition-based survival happen every so often, and if they're back to back or a week apart.
But simulacrum breaks that dynamic.
I disagree that it is limited by annoyance. It is limited by resources: by default time and gold (or at 17+, alternately by the opportunity cost of your only 9th level spell slot).
And so the DM became scared about letting the characters have any free time or finding too much gold. Bob the warrior's dreams of rebuilding a ruined castle to use as a base were shattered because it would mean Tim the wizard would get too much use of one of his spells.
Sure, but the key here is while the Simulacrum survives. They are incredibly delicate.
Even taking an ultra tough 200 HP barbarian, you end up with a simulacrum with only 100 HP. That sounds like a lot until you realize that the wizard probably has around that many HP at those levels. But he's got rage, which means half damage, right? Technically, but only for a very limited number of fights since he can't recover uses.
Copying someone who is actually worth copying (such as the caster) is likely to result in a simulacrum with the durability of wet cardboard. That's before you take into account that it can be one shot by a third level spell (dispel magic).
Yes, simulacrum has weaknesses, but it's still an insanely good spell, and one of the reasons why is you can cast it on a day you have nothing else to do and retain the benefits until you need them. Just because a glass cannon has the weakness of being a glass cannon doesn't mean it can't be too strong of an option.
Also nothing says a simulacrum can't take rests and regain abilities...actually let's not get into how badly worded this spell is.
At the levels that Simulacrum becomes available at, if you can't use the high powered monsters available to you to reach the back line, you are going to have difficulty challenging the party even without simulacrum.
Yeah, and...? Having the simulacrum is still an insane advantage in any dangerous fight.
Which is completely within the DM's purview to veto. It's like asking the CEO of a Fortune 500 company to pose for you for 12 hours for something that you could use to then commit identity fraud against him or her. Good luck. IMC, if you're on incredibly good terms with them they might do you the solid - ONCE.
A DM who permits the kinds of shenanigans you're describing is going to have issues with a lot more spells than just Simulacrum.
See, depending on the situation, it's something that could easily be very reasonable without the DM realizing they were setting themselves up. Powerful wizard wants to help you defeat the evil warlock, but is busy holding a demonic portal closed with a spell that he can't move away from! Party asks if this is so important to him and he's not going anywhere, why not let them copy him? Not like he's going anywhere.
It just sets up a lot of situations where the DM has to be ready to justify a no. Or they could just not justify it and leave the players rolling their eyes. It's an annoying lesser of two evils, shutting down a good idea that makes sense rather then breaking things mechanically or forcing you to rebalance everything.
As for PCs, it's not really an issue due to the HP limit, as I explained above.
All I can say is that I've seen it in play and haven't had any issues with it so far. Sometimes things play better/worse than they seem on paper.
Look man, if it works well in your games, I'm honestly happy it does. But see, I'm not the kind of person that looks at a potential problem and decides "You know what? In 80% of these cases, this doesn't cause a noticeable issue and is kind of cool", I look at what bad cases there are, and what prevents a user from reaching them. And if it doesn't put those cases in hard-to-reach-and/or-dubious-practicality-at-that-point (such as taking 3 levels of sorc so you can twin simulacrum), then I see it as a problem.
Maybe I'm just a pessimist.
Well, if a spellcaster casts a spell at me I try and counter it, that is no different that this. If someone summoned a monster that I didn't like I would either banish it or dispel it, again no different.
How do they know it can be dispelled so easily? Does every spellcaster in the world necessarily know what simulacrum even is? Do they even know it isn't real, given that it appears the same as the original? Maybe they'd end up dispelling the real one by accident? Or think it's simply a brother or something? Or you could have it wear different equipment to disguise itself as just another party member.
If you came into combat with two creatures, would your first reaction be to try and dispel one of them? For the DM they know it's a simulacrum, but for creatures in the world there's a leap in logic to be making and one not usually worth taking in the middle of dangerous combat.
