At low ratings it is pretty easy to bait people by loading up UAs/Darkglare/DB because they are trying to stop that damage instead of worrying about the Drain Life that will come when they don’t have ranged interrupts up/cc on DR or the healer is silenced from dispelling. I know this because I’ve been playing in low MMR range (1900-2100) and it’s easy for players to fall for little tricks.
But it’s also the reason why Destro is more popular at higher ratings. It offers more consistent pressure despite being a 3-min burst spec. It also enables other casters to get their pressure out by being intimidating. Destro can still do damage without the threat of dispels.
Aff has been FOTM at high ratings in the past because of great spread pressure, CC and defensives. Emphasis on drains and elongating the time it takes to get DoT pressure out has made it kind of a meme spec.
Despite that there are still great arena Aff locks out there and the spec is great in RBG team fights.