... and well-loved
I'd say that may be because probably most pornsites are actively maintained and constantly updated because it's their owners business.
By contrast, a lot of commerical sites owned by retailers or manufacturers are probably rarely visited by their owners, who are too busy selling shoes, or bathroom fittings, or package holidays, they've paid someone else to set up the site, and it only gets checked infrequently if ever.
And then there are hobby sites or blog sites or social where everyone + dog (usually amateurs in IT terms) can upload stuff.