I mean, "tech wise" is incredibly generic. Electricity itself is pretty much essential and something I'd have a hard time living without.

As for more recent tech, the internet. I can "live without", but a lot of stuff I do for entertainment and self education needs it. There's also the discovery, finding out about new stuff that interests me, that'd be much harder without the internet.

Even if you removed several sites, if the 'net was something like it was back in 1994, there'd still be enough content and people around to get good amounts of information back and forth, plus file sharing.

As for time saved, just think about trying to discover, not even acquire or read, just know about, some 2 or 3 books in an "obscure" subject, something that your circle of contacts is unlikely to know anything about, that local book stores probably won't have. Same applies for games or media that said circle of contacts are unlikely to know about. Basically, you have to take the dive and explore and, depending on what you were looking for, you'd come empty handed, or have to contend with a "better than nothing" alternative.