>> That you've worked places that rebuild/gut every 2-3 years... I don't know how 'normal' that actually is, save for JS front-end stuff, which seems to almost necessitate it.

I lot of the places had huge portals, e-commerce sites, or multiple transactional application sites. Many of the places I worked transitioned into and out of various platforms.

One place was a huge .Net place, had some run-ins with MS and then decided to move any and all of their stuff completely over to Salesforce. I heard three years later, MS lured them back and they went back to being a full blown .Net shop.

One big motorsports company I worked at had 8 product lines all with an accompanying e-commerce site. They were literally in a 3 year "refresh" cycle. Every three years all the sites would be re-designed, rebuilt and re-released. The company was a huge .Net shop and they always used MS for their DB's and backend. Once libraries like Knockout and Angular got popular, it just became a three year run of JS frameworks/libraries battling it out to see which one we used next. The sites literally went from Knockout to Angular to ReactJS to Vue. By the time they had gotten around to ReactJS, I had already left the company, but the cycles they were on were just crazy and continue to this day.

Another huge corporation I worked for had multiple portals. We literally re-built them all within a 3 year period from scratch, then it was in maintenance mode for a while until we got a new CIO who then decided he wanted to move to a different stack. Rinse, repeat. Less than 5 years, the cycle started all over again.

A health care company I worked for wanted to build a Wellness app for their clients (this was a new thing back then). Their direct competitor had one and they figured they needed one too to keep up. We built that in the span of about 18 months. Gets released, gets rave reviews, we have another year of front-end and DB improvements, everything going smoothly. Apparently the competitor launched a mobile app for their Wellness app. This was about a year before responsive design really took off. They panic, nuke our Wellness app, and then had two teams (one Android, the other iOS) hastily build the app and release it.

Just started working for a huge health care company. First project I was on was to take several different billing systems and create a transactional app for two teams so they could manage everything out of a single app instead of using multiple systems to log into and out of constantly every day. We built that over the course of three years. Then the initiative was to replace ALL the billing systems the team was using with a single system. Apparently the first meeting all the executive types wanted our entire team back on the project to give direction and come up with a dev plan. Again, just about the 5 year mark, all of our work got nuked.

In hindsight, it was never always some new framework. There were consistent external or internal factors (good or bad) that was driving these decisions. Its kind of weird finding out this is by no means normal, but when you spend so many years and the same things keep happening, you just assume this is normal everywhere.