The default healing rules are meant to be cinematic not realistic.
There are variant rules in the DMG which are much grittier - plus, 5e being as popular as it is, there have been many variants developed. You can certainly find one to your taste.
I think your missing the point by focusing on something else. Look at it a different way. you can celebrate making it back from the fight by drinking a cask of brandy& the next morning the hangover is affecting you more than the fact that a dragon was feeding upon your liver(it's okbro healing word) the morning before after the kobold servants kept (it's okbro healing word)stabbing you in the lungs (it's okbro healing word)on the way to the dragon that kicked things off by breaking both your arms (it's okbro healing word) and legs (it's okbro healing word)
The complaint is not that d&d doesn't have lethality & walking wounded states akin to fate (which can get very nasty in deep death spiral territory if conceeds aren't used). The complaint is that you need to look to things like spawn deadpool & wolverine for a reasonabe "cinematic" comparison to even an average PC. That wasn't always the case in d&d as 1st/2nd, 3.x, (I skipped 4e) all had PCs who needed to put in some level of effort to not die from sheer stupidity while 5e you almost need to try hard to die intentionally after level 5 or so & even then will still probably need to tell another player to let you die because that was your goal when you became a wizard tank taking on literally everything in the session face first for the second session in a row.
edit: the gritty realism rules are a farce but I guess we could add loony toons to spawn/deadpool/wolverine