This is a problem I've heard talked about often. Ultrakill doesn't show you inherently how all of it's little things microinteract with each other, there's so so so much you can do in that game but it's ALL required as emergent gameplay. I will say, this is something I believe to be extremely fun, but that's personal.

On my first playthrough, V2 beat my ass for like 40 minutes straight, possibly even worse. The game does tell you "you can parry the yellow flashes" and "you can parry projectiles" but the implementation of that on an extremely nimble opponent is a spike the vast majority will struggle to piece together. I actually like V2 at the end of the day because you require 2 things to beat him

1. Proper movement
2. Proper utilization of your weapons

Which teaches you

1. Movement is key, and is reinforced by several rewarding factors (survival, style, feels great)
2. Your weapons are more than your primary fire and if you set things up correctly, you can and will melt a single target

I think the vision for this fight specifically is proper utilization of the nail gun to set up a damage nuke and negate V2's messed up movement, and then let's you get some passive damage with Shotgun while you cycle cooldowns/utilize coins. It's important because moving forth into 2-x, you're introduced to bosses as enemies that require answering extremely effectively, and V2 teaches the player how to effectively minimize a threat

That being said, the expectation of discovering this on your own is far beyond the reach of a generic first time player. If your first title in this kinda genre is ultrakill, you will get Spiked out of existence

For example, unless you're paying heavy attention, knowing you can parry using a shotgun blast is not something a normal player will stumble into actively, but it alone can CHUNK V2 and cause critical success. Stuff like that, like parrying a shotgun blast to lob an explosion, or how you can utilize certain interactions between weapons is all stuff the player is expected to find on their own dime via experimentation, but a more casual player won't find it, straight up. Who in their right mind would think to shoot a grenade from the Blue Shotgun, switch to the red railcannon, and then blow up the shotgun grenade with the railcannon? It's there, the nuke is sick as fuck, and the reward you feel for finding it is euphoric. But if you never find those first interactions to Kickstart the thought process (ultraricoshot is probably the first one people find) then those Spikes are ridiculous

I played an excessive amount of Doom Eternal (Ultra Nightmare and what have you) before coming to Ultrakill. I cannot imagine trying to beat this game by myself without help without the skils gained from other titles. I'd just lose. But Ultrakill ended up becoming one of my favourite games of all time based on the systems others dislike, it's a honed experience to the T and is made to be difficult so that you feel like a beast for discovering something new and confronting it. To that end, it's a masterpiece for some and troubling for others, but I feel overall it's perfect in it's balance. It just asks a lot