I don't disagree that de facto it makes it easier to have a company sponsor you since they know who are a good worker. I just wanted to point out that in regards to the GC application it has no influence.
Do you happen to know if all your co-workers got their residency through employment ?
I only know one H1B who is attempting to get a GC through her company, she started the process 3 years ago and is not done yet.
OTOH, in my (limited) experience, I have worked closely with a total of 4 H1B employees, and at least 3 of them are now permanent residents or citizens. I can't speak to the overall frequency of this happening, but that's my anecdata.