You can't have 15 years of experience in [whatever thing] when [whatever thing] didn't exist 15 years ago.
Note: 15 years ago = 56k internet, paying by the hour, for the 0.xyz% of select few people on the planet
Some of the details have changed, the languages, the size of the databases, the devices involved, and a million frameworks for front end have come and gone.
Some of the time 20 years experience feels like 4 years experience repeated 5 times with different buzzwords. The same screw ups, the same lack of understanding from missing the same point, the same management wish to do SEO and security later. Or to budget 2 weeks for bug fixing.
Now you know 5-10 languages all with good and bad points so tune out most of the zealotry of the latest fashion to try and get to real distinguishing points.
All that experience can help a lot. It's far from dead. We can even have the same emacs vs vim argument that happened in 1990.
To quote the other comment: "20 years experience feels like 4 years experience repeated 5 times with different buzzwords".
There are two things which come to mind and that I'd like to point out.
- Each 4 year cycle is bringing less and less experience. The guy who is starting now is going to work for at least 45 years. We could say that it will be a tremendous amount of experience, but it's more likely than he will not be able to sell > 30 years of experience. [it's challenging and not specific to tech work]
- There exist no people with > 30 years of experience. That's not to negate the handful of these guys in the SV and a couple of research centers across the world. Relatively speaking, the amount of people with 30 years of experience is roundable to zero.
- Corollary: It's difficult to know what it's like to have 30 years of experience in the current market.
- Final word: Shiny technologies are only affecting the 20 years old bro coders in the 70 hours web startups. The bunch of the jobs are still in old school industries like medical/aerospace/finance/government/contracting who stick to old school tech and never upgrade.