I mean technically but that’s semantics. It straight up one shots you unless you have some way to cheese it. It’s also something that the devs chose to add on top of what bosses normally do instead of creating brand new bosses. The echoes are basically a separate mechanic that just happens to coincide with the boss fights rather than being something the bosses themselves do, echoes can even spawn while the bosses are staggered. If the they were to be taken out of the equation boss damage would barely be a factor, their HP would be the only thing that can prevent you from timing a run at higher tiers.