I think badger brushes have become popular when wetshaving became more of a hobby than a necessity.

Pretty much all the old-timers that I know were using boar brushes. My dad used one in the 50's and 60's, and that is what I used when I started shaving in the late 70's. So did my grandfather, etc. Many of the barbers I talk to don't even know about badger. Pretty much all the vintage brushes on ebay (rubberset, etc) were boar.

I am sure the old English brush companies were around, and it may have been an issue of cost, but it seems that boar was more common back then.