Standing 4 wouldn't give enough advantage to do it, if you mean standing 4xxBat summon, remember, it's hard coded, the game simply wont let you do it until the combo is systematically over.
Summoner's options post knockdown, while still considerably oppressive, is probably not what most people have an issue with, he's arguably an inferior zoner to HQT Predator, who's armor utility is also limited but still far more usable, and it hurts like hell when it does hit. The situations when Sky Drop can reliably be used (which can probably be counted on one hand), Summoner gets himself a 15% knockdown.
The witch-hunt as far as I know is geared towards Summoner's hard-to-blocks and overall damage potential, both of which are significantly neutered by Bat summon being hard coded. The armchair critics should draw the line as to where their own quality of life wishlist is coming into play and risk fucking over the other variations.
And I'd like to remind everyone I'm a Warlock specialist, I have no agenda to use Summoner myself regardless of what happens to it.