Let It Die is a Souls clone in the sense that it's combat mechanics are most like the Souls series. Besides that, and a general sense of punishment which isn't exclusive to the Souls series, it's not really a relevant point. There's nothing special about Souls and nothing special about the fact that Let It Die has its combat. To be honest, I don't even understand what your point is.
I completely disagree with your assessment. The game's free-to-play mechanics, aside from one aspect, doesn't really control how powerful you are. Your power level is more depended on leveling up your skills and crafting stronger gear. F2P has no effect on the former and only indirectly affects the latter in rather meaningless ways (you can spend death metals on coins, if you run out, and to spend up the crafting timer - but both are really poor uses of them). The game is kind of grindy in some ways, to be honest, but oddly enough, the F2P mechanics don't really effect that grind much. They don't give you a bunch of materials, they don't instantly level you up, they don't level up your skills, etc. The premium pass gives you more inventory space and free elevators rides, which is nice, but not really powerful.
The one aspect where F2P can become pay-to-win is using death metals as credits/credit-feeding. Being able to instant revive with full health (and an invisibility effect) is really, really good for obvious reasons; in theory, you can cheese any fight with this (one big exception being a deadly enemy type which prevents this, which may be poor business sense lol), like you can credit-feeding in certain arcade games. However, you really don't want to do this (especially on the lowest floors), because what you really want to do is spend your death metals on making your storage huge (100+ is a bare minimum really). To say that the game depends on this kind of credit-feeding (aside from refusing to take a loss) would be kind of ridiculous and it's the only F2P mechanic that is P2W.
EDIT: Not only in the game fairly generous with death metals, if they ever fix it so that the quests which most often give them away, limit quests (kill every enemy on several floors under certain conditions before using an elevator) wasn't so easily broken by haters or environment hazards), you'd effectively be doubling the free access to them. Really hope they fix those quests, if only because they are really interesting mechanically.
Perhaps you are referring to the hater mechanic, which scales with your total progression rather than character progress? There may be an issue there (for new characters) but that's only after reaching the 3rd tier, which is a couple dozen hours into the game - and going by what you are saying, I don't think you've played that far. For haters though (and bosses and pretty much anything), the mushrooms (basically the game's consumable spells, in Souls terms) are so fucking good they can trivialize most encounters and turn to the game to be more about resource management than anything else (especially during those scary treks into higher floors where you have no idea when you'll reach the next elevator). By the 2nd tier, you have invisibility and decoys, super-strong stuff.
I've put 50+ hours in LID and haven't spent a cent (which I actually feel kind of bad about - I would probably throw a few dollars down out of gratitude if I didn't quit cold-turkey). My storage is sufficient even for my material hoarding, I've upgraded tons of armor, mastered the first three tiers, etc. The game doesn't give a lot of reasons to pay up, to its own detriment (I have to imagine at least an item store is coming at some point). This is the common opinion I'm hearing on GAF and twitter. I don't want to make it seem like LID doesn't have flaws or that it is perfectly balanced, but being F2P seems almost irrelevant to that. If you are going to complain about F2P mechanics in games, I can't think of worse game to choose to do that with. Perhaps this is a case of git gud?
LET IT DIE isn't a Souls clone, it's a roguelike.
Calling it a rogue-like is just as misguided. If anything, it's more like Chalice Dungeons (less random) in Bloodborne than like Rogue.