Whether that person is talking their book or not, there absolutely has been an app explosion. Github & the app stores have all reported as much over the last year.
I also have repeatedly experienced the phenomenon of nontechnical people having built custom software to run their businesses. A lawyer friend was first, sending me a link to his GitHub(!), where he has built a custom client intake/practice-management application to work as the firm works. He's not the only non-technical lawyer I know who has shared vibe coded apps with me.
I personally build many, many single-use apps than I ever would have before. Gnarly debugging sessions can be greatly simplified by inserting a custom piece of disposable tooling/etc. I am not a Mac programmer, but I now have custom Mac apps to solve problems that only I want solved. Do these count?
Honestly, I would be a little surprised if anyone posting on HN did not have some personal exposure to the explosion of apps.
The closest parallel in history I can think of is the proliferation of spreadsheets in the 1980s.
On the Home Assistant and Jellyfin reddits you'll see tons of vibecoded dashboards and plugins people are putting together - and those are just the ones people are sharing.
I personally have been building a bunch of little personal apps for my home that aren't worth the effort of sharing - like a customized dashboard of the Trimet buses closest to my house. The cost to build the initial good-enough version was literally 5 minutes plus another 10 to test and deploy.