The FOSS movement is not a monolith. There are many individuals and organisations pursuing many different goals, many of which are at odds with or even antithetical to the goals pursued by Fortune 500 companies.
The kind of company that won't touch the GPL with a ten-foot pole is not the kind of company that's looking to be a good participant in the FOSS space. The purpose or merit of appeasing them by switching to a non-copyleft license like MIT is not at all clear to me.
Some of the most powerful people in the world are not entitled to the free labour of under-employed hackers building cool things in their spare time without any expectation of reciprocating, which is the only significant thing that the GPL mandates which MIT does not.
"We'd use this, were it not for the GPL" = "we'd use this, were it not for the obligation to give our improvements back", which is a massive red flag. Fear of the GPL boils down to the simple fact that these entities don't care about FOSS, they just want to build their proprietary castles on top of public beaches.