Why do Pega documentation URL's change so often

Why do the Pega doucmentation URL’s change so often. This is very disturbing when developing an application and I want to read some documentation. When opening the URL that I saved in my bookmarks is not working anymore, it completely gets me out of my develop ‘zone’. And that really bothers me.
Not only is old link gone, searching in the Pega documentation is not becomming easier in the last few years.

For example, I was trying to open the URL “https://docs.pega.com/data-management-and-integration/87/repository-apis” to read specs about the Pega Repository API for Pega 8.7. Pega 8.7!!! This version is not that old.

Pega, please use perma links or do not remove old links. Think about your users who use and read your documentation!

@dvmierlo We appreciate this feedback and sincerely understand your frustration. The recent changes you and others are experiencing are a step change toward a significantly improved documentation and search experience across Pega’s digital ecosystem. As with any major change like this, we’ve had to weigh the pros and cons of what’s necessary to achieve the end goal; some resulting in decisions that admittedly may cause some confusion during this period of transition. If you’ve not seen it already, please check out this recent Support Center post providing some of the high-level rationale for these changes, as well as a few tips on how to best find and access content you may be looking for.