The "adventuring day" is a relic of times when your entire campaign was exploring a megadungeon and you ran from one encounter to another, back to back, all night long. But barely anybody runs their game like that these days and the rules just never caught up with reality. Some people suggest having a constant time pressure on the party limiting long rests, and while it can work, it also puts a straitjacket on your story pacing where balance flies out the window if you ever let up on the pressure. "Guys, the apocalypse is merely hours away" quickly gets old when it's been that way for months.

Well, that and 99% of the rules involve fighting or exploring. Anything the rulebooks have to say on social interaction boils down to "well, you just talk to the DM, and sometimes they might have you roll a d20, just figure something out". D&D isn't really so much a role-playing game as it is a weird dungeon-crawling boardgame with some role-play elements. Sadly, people are allergic to trying new systems so instead they'll just try to bodge the one big-name king of TTRPGs, D&D, into doing things it was never built for, forever leaving them wondering why driving in screws with a hammer isn't as fun as they expected.