As someone who replays P3/4 at least once a year I gotta say I'm used to it by now, but given mainline SMT ditched it I was baffled that it is still in Persona 5.
Other games get by being plenty of challenging without a stupid mechanic like this. P5 holds your hand in a lot of ways and that's good, it's meant to be accessible. It allows you to restart bosses and from the nearest checkpoint on random encounters, the exhaustion system from P3 didn't come nor did party members staying dead if they fell during battle. The game gives you a nifty autoheal button, a assist button to automatically choose a spell that exploits weaknesses from any of your personas and gives you map markers to run after for a lot of shit.
Yet still, there's the MC Death = Game Over mechanic, which feels out of place given how accessible the rest of the game is.
I've never had the protag die due to my own fault, but I sure did to turn 1 mudos/hamas or crits obliterating the protag, and honestly that's my issue with it.
It doesn't make the game any more challenging, it doesn't "raise the tension" of random encounters, but it definitely is frustrating just to randomly lose time on RNG, and that isn't something determined by skill rather than a random roll where the game decides to waste your time.
And honestly? Out of all the features P5 has to make the game easy, I'd rather have that mechanic out in trade for all the QoL shit they put in.
