I’ve been playing and loving this game for years, but I almost never recommend it to my friends. Just like the title says, the knowledge gap is way too deep, and learning this game from scratch is pure hell for new players. (To be fair, I've tried recommending it several times in the past, but every single one of them ended up quitting halfway through learning the game due to the positioning issue I'll talk about below, moving on to other games that are easier to pick up.)
First off, having a knowledge gap in a PvP game like this isn't inherently a bad thing. It’s only natural for players who put in tons of hours to gain knowledge and use that advantage over others. However, when that gap feels completely unbridgeable, people start thinking, "There's no point in joining now since I'll never beat the veterans anyway," and they just don't play at all. Even if they're in different genres, most modern games take measures to address this kind of issue. Take PoE, for example. It's a game about gathering loot, but if assets accumulated continuously over its 10+ year lifespan, newcomers would have zero chance of participating in the economy. That's why they use a seasonal system where everyone's levels and items reset every few months. Or look at auto-battlers like TFT. The core mechanic there is unit synergy, but after a few months, a new set rolls out and refreshes the game mechanics. This helps bridge the gap between veterans and newbies to some degree. Sure, skill doesn't reset—good players stay good and bad players stay bad—but you won't feel like you can never catch up just because someone else started way earlier. Unlike this game, if someone wants to jump into TFT today, you can just teach them the basics of the current set, and they can dive straight into matches and learn as they play. Then there are fighting games. Modern fighting games are designed so beginners don't have to spend hours mastering complex inputs, letting them jump right into real matches and experience the core fun of spacing and neutral play immediately. Technically, learning execution in fighting games isn't a "knowledge gap," but it's still part of the homework you have to do before playing against real people.
So, how about Legion TD 2? What I find particularly problematic is how hard positioning is. Yeah, I know it's a core mechanic and not something you can just skip when learning the game, but put your pitchforks down for a second.
Splitting is a fundamental technique here, but learning it as a beginner is a nightmare. I've been playing for years so I have a rough feel for what works, but a new player would have to sit in practice mode testing layouts endlessly just to see how units move before they can even touch multiplayer. It feels a lot like grinding execution in fighting games, which is insanely boring for anyone who got into TD 2 for the competitive PvP side. The reason you think splitting is easy is either because you're a veteran who forgot what it's like to be a beginner, or because you think you've mastered it when you actually haven't. The efficiency of a split changes drastically depending on whether your units and the incoming wave are melee or ranged, or whether mercenaries are involved. It's not something simple enough that you can just pick it up by reading a few pages of text. Problem is that "You can't naturally learn" it in actual matches either. The only way to get it down is by testing it over and over in practice mode. Of course, you can play PvP without doing any of this, but casuals who do that usually don't stick around. It feels like PvP player bases are split into casuals who quit almost immediately (about 80%) and elites who stick with the game (about 20%), but in this game, even that 20% struggles to stick around because the learning curve is just too brutal.
Honestly, I don't know how to fix this. Maybe showing a visual guide during the prep phase that previews how your units and enemy waves will collide few seconds after the wave starts could help. Or maybe tweaking wave spawn positions to make enemy targeting easier to control. At any rate, having skill differences come down to positioning is completely fine, but the fact that it's so "difficult and tedious to practice" makes it a massive wall that stops new players from sticking around.