genuinely curious, has there been any evidence in the past of large corporations decreasing the quality of programming languages that they have influence over?
Companies do periodically try to take over C++. Several have sought to throw their weight around by sending numerous extra bodies to vote at selected ISO C++ Committee meetings. They do not often succeed at that, but some have continuously outsized influence on the process, at all levels, just by their sheer amount of participation.
The people they send to meetings on a regular basis do a great deal of important work, and they often disagree among themselves. But sometimes marching orders evidently come down.
There was a recent concerted effort to define a process to determine when and where backward ABI compatibility should be abandoned, which would have made it much easier to bring about such occasions.
Maintaining a list of individually unobjectionable principles seems innocuous, but it is via the principles omitted from the list being thereby made harder to appeal to that you can get bad results. And, the more there are, the easier it is to reject this or that request.
I know some people took issue with Oracle buying Sun and controlling Java, and I think it had something to do with licensing. Perhaps that doesn't qualify, though.
I was ... let's say "apprehensive" ... when I heard Oracle had purchased Sun, and thus control of Java.
However, with the exception of some communication missteps around the licensing changes (which actually ended up in fully open source JDK, as opposed to the mostly open source JDK in Sun's time), Java has actually done great under Oracle.
Amazing what having resources can do for a project, eh?
I mean, I'm not thrilled with the licensing model around GraalVM (since it's another "mostly" open source situation), but business is business, I guess. I'd personally prefer that they treat it the same as Java proper, and fund it via support contracts/subscriptions.