If so, it's probably only because young adults are more likely to use the internet and therefore have problems that can be solved by the internet. The internet can't really fix your problems if you don't use it in the first place. Or maybe it could, but you will never know better.
Twenty years ago, this might have been true. I don't think it is today. I'm 60 years old, and while I'm somewhat unusual in that computers and tech have been part of my life, both personally and professionally, for half my life, I would have to think pretty hard to come up with someone in my circle of friends and relatives in the 50-80 age range who doesn't use the Internet. My 80 year old aunt has a desktop, an iPad…
I suppose SV companies are going to tend to solve young adult problems because they are composed of young adults. It's what they know.