Healing exists in video games for balance reasons.

You mean we can't just chug entire bottles of pills [L4D2] or eat random herbs [RE] or do... something to a ram's head [Rastan] and instantly return to full health?

Games have been lying to me for decades! 😮

Edit: speaking of L4D2, this is where the "Realism" mode would come into play and piss off any normies playing. You die almost immediately when playing Realism because amongst other things friendly fire from a shotgun is quite lethal irl.