"Are assassins bursting your carry at the start of teamfights?"
The answer is YES, and for me Exhaust was the only thing stopping them from doing just that...
"Is Kennen ultimate destroying your team?"
Again yes, but guess what...
"Then we’ve got the summoner spell for you: Exhaust!"
Well, not anymore.
"However, Exhaust is pulling too many extra strengths beyond “anti-burst” - even making its targets easier to kill."
Isn't that what its supposed to do? Make a key enemy easier to focus? Aside from exhausting enemy ADC...ehm, sorry, "marksman" on lane or using it against divers like Rengar or Khazix, what else is so op about it? The only class that extensively uses that summoner spell is Support, Mid or top occasionally when they come up against assassins.
"There’s nothing wrong with a summoner spell serving multiple functions"
Well f*ck Riot you beat your own arguments with the changes you do.
"but when a defensive summoner spell is about as good for killing people as an offensive one like Ignite, it’s time to trim some fat"
Exhaust stopped being a defensive summoner spell long ago, so don't you worry about that, because exhaust is...ehm, sorry, "was" used to win 1v1s and weaken a certain AD damage dealer. Ignite on the other hand is primarily used to cut the healing of blood suckers like Vlad or Swain nowdays and we aren't nerfing that because of it.
6 and a half years of playing this game and after countless atrocious nerfs and changes, this is one of those that crosses the meta line. Now exhaust will become ineffective as Supports primary Summoner spell, and other Supports will probably swap to ignite. Some have already done it to cut the Summoner Heal and it has proved semi-effective.