Yeah, I doubt you can still use tech you used 5 years ago, never mind 10 or 20.

> But when I explain this in interviews I feel like hardly anyone buys it.

If the interviewer wants to talk about one stack, that's likely the one you'll be using for the job, or the one they have experience with. And please don't tell them "but I can get up to speed in no time in any stack", nobody wants to pay a freelancer to get up to speed.