Because negative hp is nonexistent, healing is by far most efficient when used on a creature with 0 hp. This can encourage a whack-a-mole playstyle wherein players are healed minimally (e.g. with healing word or with 1 point of Lay on Hands) to bring them back from unconsciousness, just to go down again as soon as they take damage.
This isn't necessarily unbalanced, but it is gamey.
Typical Treatment
To discourage whackamole, one can suffer a level of exhaustion when reduced to 0 hp. This has the added benefit of making fights feel gritter and more consequential, like a simple version of lasting injuries.
What this treatment does not address is the actual difficulty in healing enough damage to make preventative healing viable. Healing word and cure wounds are single-target chip healing, and even the infamous healing spirit is really just mass chip-healing in combat. The first good non-chip healing is probably the heal spell; before then, upcasting cure wounds is the best option.
The best preventative "healing" by far is renewing temporary hit points, such as the artillerist's protector or Twilight Sanctuary. Perhaps such effects should be more accessible (via a spell, for instance). Or perhaps there need to be better options for single-target non-chip healing (e.g. stronger spells or feats that improve healing; the Healer feat is an excellent example). Or maybe KOs are rare enough anyways that this isn't a problem at all.
Because negative hp is nonexistent, healing is by far most efficient when used on a creature with 0 hp. This can encourage a whack-a-mole playstyle wherein players are healed minimally (e.g. with healing word or with 1 point of Lay on Hands) to bring them back from unconsciousness, just to go down again as soon as they take damage.
This isn't necessarily unbalanced, but it is gamey.
Typical Treatment
To discourage whackamole, one can suffer a level of exhaustion when reduced to 0 hp. This has the added benefit of making fights feel gritter and more consequential, like a simple version of lasting injuries.
What this treatment does not address is the actual difficulty in healing enough damage to make preventative healing viable. Healing word and cure wounds are single-target chip healing, and even the infamous healing spirit is really just mass chip-healing in combat. The first good non-chip healing is probably the heal spell; before then, upcasting cure wounds is the best option.
The best preventative "healing" by far is renewing temporary hit points, such as the artillerist's protector or Twilight Sanctuary. Perhaps such effects should be more accessible (via a spell, for instance). Or perhaps there need to be better options for single-target non-chip healing (e.g. stronger spells or feats that improve healing; the Healer feat is an excellent example). Or maybe KOs are rare enough anyways that this isn't a problem at all.