You seem to trying to express a negative response to the fact that these companies create design frameworks. I'm interested as to why you feel this way?
Having partially reviewed a couple of these, I'd say quality varies quite a bit so be sure to dig through the code to see if you'd be comfortable helping maintain that. Always be sure to review the license! For example, Microsoft Fabric is MIT, but the assets (fonts and icons) are under a separate license.
No real intent there. It's good to have large organizations donating libraries to open-source.