Basically, dabbling in PCs used to be really expensive relative to today. ((The details matter of course) but basically a PC and software in the early eighties was many thousands of dollars in today's money.
That really accelerated around '95 or so with Windows 95 - anything that couldn't run it became almost free overnight.
EDIT: You could get an assembler/dis-assembler for the ZX-81 for $20 (1982). Also at the time a lot of software was "shared" between enthusiasts.
But get into anything like a PC clone--much less anything with a hard drive--and the prices went up fast.
Of course the real Apple II competitor from Sinclair was the ZX Spectrum.