It definitely has its perks for publishers shipping physical products. Unsold inventory is a killer and publishers need some way to know how many copies to print whether it be through KS or subscriptions like Paizo has.
Generally I would be curious if there’s a reason publishers that largely sell PDFs that are mostly done by the end of the KS campaign wouldn’t be better off going the patreon route like
@Whizbang Dustyboots suggested. I am incredibly ignorant to the realities of publishing so I am sure there are plenty of reasons. I know I am more likely to say “sure, I’ll throw $10 at that campaign” vs. a $5 monthly patreon subscription where I don’t really know what I will get month to month.