honestly, i think you guys are just being difficult for the sake of it. the average character lvl to be at in order to have 100hp is like... lvl 13 or something? if you're that high and the dm is hitting you with a 2d4 poison, then the issue isn't the rules being easy, it's your dm not understanding appropriate challenge. if you are TRYING to kill your players, it's incredibly easy. all it takes is a roll or two in the DM's favor to royally screw a party. the more players there are at a table, the easier it is for them to win, obviously because it can come down to just simple action economy being so grossly in their favor. but a good DM can create some deathtraps really pretty easily for any size party. deborah ann woll (true blood, daredevil) just started playing a handful of years ago. she DM's and she's really pretty great. one of her signature moves is creating encounters that you cannot simply outroll the DM. the encounters aren't HP sponges, even if it presents itself that way.
there are also modules that are specifically designed to be brutal and unforgiving to your players. one of my weekly games is tomb of annihilation and there are all kinds of traps and puzzles and monsters that will just outright kill players if they aren't playing really well. and even then... out of the 6 players we have, we've had close to 15 characters between us all (in tomb of annihilation, death is permanent. no revive spells will work at all. the entire hook for the story is that revive magic has stopped working, and anyone who has previously been revived in any shape starts withering away). the DM has actually said on multiple occasions that he re-wrote certain encounters because it would have most likely ended in a tpk. so instead of all of us dying, it was only 3/4's of us.
i WILL concede that 5e has basically done away with "save or die" mechanics, which i'm happy with, personally. there are still a few "save or suck" spells like feeblemind and such...