It might be an easier metric to gauge the growth of homebrewing by the expansion of not only the supply chain, but also the ancillary craft beer boom that has risen since the 1970's. I started brewing in 1991 while I was in college. There were no LHBC's or LHBS's in the entire state where I lived. I had one choice for homebrew ingredients: The US mail and my bacchus and barleycorn catalog. They were one of the first major players in the homebrew world, and they're still around all these years later.
Now, it seems like every major and minor city has at least one LHBS (if not multiple) and many big cities have way more than one LHBC. Ours has two, I think Tampa has three or four, Orlando the same. Then, take a look at how many craft beer breweries have opened up. I think in the late 70's & early 80's, there were two craft beer breweries. Now there are well over 2,700 and the number is expanding.
BMC, which still dominate the market share, are steadily losing ground and are frankly scared sh!tless as to what to do about it. They've been playing strong arm tactics with distributors to prevent craft from taking up shelf space and tap space for years and are fighting a losing battle. They just don't understand the nature of craft beer and how to properly market it. The best they can do is buy up successful breweries in an attempt to survive.
So, yeah homebrewing is helping to change the landscape of beer itself.