Lakesidefantasy
Hero
In earlier editions my group made up house rules to make healing more like it is in 4th and 5th editions. Or, we just ignored it. (We ignored a lot of things when we were kids.)
For me, the healing on rest rules aren't so much about plausibility as pacing. I like running slower paced games with a reduced focus on combat, so the alternative slow recovery rules in the DMG help ensure that combat still has meaningful consequences. I'd use the standard healing rates if I was running a dungeon crawl adventure, or a fast-paced epic save-the-world style plot.