Big companies are no longer significant in terms of IT vendors. They move too slow, and spend very little compared to consumer market. Billions of smartphones versus millions of corporate desktops means that enterprise IT is a secondary market. Big companies do big business. They don't play with the small stuff.

1000Gbps does NOT need Cat 5e. Cat5e gives you more spectral capacity than Cat 5 so makes your cabling more tolerant of bad installation.