That stake is premined...

It wasn't "premined." But it was mined for a specific purpose and has so far mostly not been used for those purposes. It was specifically stated that the stake would NOT be used for voting on the platform. So, they get around that by delegating it to other projects of their choice to be used for voting on the platform? The effect on users/investors is the same and contributes negatively to demand for STEEM and SP.

Most platforms have a hard time competing since STEEMIT has no beneficiary fees.

Well, that sucks for the other platforms. Maybe they ought to figure out different revenue models and create interfaces that are actually appealing to users that aren't already in the Steem bubble and mostly just looking for more ways to acquire and dump tokens. Because other interface developers aren't good at meeting demand and creating appealing products isn't a good reason to go back on your word and dilute actual investor influence.

If they burned a part of the stake...

They'll never do that. I've been banging that drum for a couple of years now. They don't care and most of the platform has the same failed mentality of "Delegate to projects, guys!" You know...the stuff that consistently makes STINC look terrible/incompetent (because they suck at making good decisions with their stake) and drives away good investment.

They seem to still be uninterested in making any smart moves.

I think it's more than being "uninterested." They're just wholly incapable. I would support protocol changes that fork all official STINC accounts out of Steem.