There should be no reverse team damage with an incendiary or molotov after a couple of seconds have passed. Players who willingly run into fire should receive 100% of the damage.

Also, you should never die more than once to the same incendiary. I recently had a teammate in a domination game stand in the flames for an extended period, resulting in my character dying on respawn.

Ultimately, it makes incendiaries far less useful and the game less fun.