I think he definitely has a point in regard to the spawning monsters. I've seen several different people play this and the various enemies throughout the game with no-hit box startup/spawn animation slows the game down. I see players attacking the monster and hitting nothing constantly. You have to wait for them to finish that spawn animation before you can do anything, and the player is often already within range to attack when the spawn animations start. Just off the top of my head, the zombies, sand people, and mummies all do this. It would have been more effective if they introduce the monster with the startup animation, but then have the rest of that type of enemy fully spawned.
I still don't agree, this is not about what people do, it's about what they should be doing instead. Take for example the Souls game which in my opinion have a very similar philosophy to older Castlevania games, it's all about timing your attack considering animation windup, distance, and so on. I could go play that and claim the hitboxes are broken (they are but for different reasons lol) because when fighting NPC summons for example i cant hit them during the summon animation, or during the healing one, or again when a grab animation is in the works on bosses, but that's not how its supposed to work. I don't want a game where i walk around and everything i touch explode the moment i touch it and i can just whip around like a madman. To go back to your examples specifically, the zombies start being hittable the moment they're halfway through the ground, to have them get the hit the moment their heads stick out of the floor would effectively make them completely useless, what's the point of having an enemy around if it can't pose any sort of threat? in regards to the Sandmen, it's also very readable when is it that you can actually land an hit on them and it's specifically from the moment they become solid, you can see them gathering sand from the floor and having some transparency quality to them until they are fully made and start walking at you, again, it's about timing the attack at the right moment to avoid risk of being offguard and catching a hit, that's EXTREMELY important in a Classicvania game in my opinion. Same goes with the mummies, they aren't hitable until they are on the foreground, that can be read easily by their arms being fully pointed at you. I think people like who you watched play in the videos are not reading what's happening on screen and that's their fault, not the developers. Only thing i could agree with is the axe from Axearmors being indestructible, it made sense in the original as they were chained to the enemies and that would make you understand they would go back to them after being thrown, here's something is missing and they could have fixed it by sticking to that design idea.
On another note,another thing I noticed lacking after replaying the HCR again and again, does anyone else feel like a scoreboard is needed? I can't keep track of my scores and that's a huge missed opportuinity to even add an online leaderboard. Again, together with the full screen option for the DS titles, hope this gets patched in eventually