But today? People have access to all the porn imaginable, can access it from a very early age, and can do so with absolutely no physical evidence---and if one erases browser history after every visit---no evidence at all.

You mention 50 tapes. Imagine how many "tapes" a bigger harddrive today fits? I imagine hundreds to 10s of thousands (all depending on resolution and encoding of course). Point is, a HDD today could easily store 200x those porn tapes (say 10,000 hours) video vs tapes maxxing out at 1-2h avg commercial VHS tape (x50 = 50-100 hours) at better quality.

I store my entire book and audio book collection on my phone because I move and just don't want to lug anything around, unimaginable in the 80s/90s with the tapedeck walkman, casettes, and VHS as a near-term thing coming.