I used to work for a GIS company. All of these companies' tools are based on whatever software development platform was current when the project was initiated.

I used to work for a GIS company. All of these companies' tools are based on whatever software development platform was current when the project was initiated. The mapping tool may grow to be 8, 10, 15, even 20+ years old and new features are continuously added, but never is the underlying software platform upgraded or the tool rewritten. I'm not sure why this is or even if it is peculiar to GIS, or just more visible compared to the many slow-to-upgrade software fields which don't have a UI or which do more server-side. Also I think some of it is also driven by having one or more big customers who themselves refuse to upgrade. The effect was particularly visible as an outside team was developing a greenfield iOS app for our data at the same time as our team maintained their old-new Windows app. The iOS team was able to, as they say, "move fast and break things" and gain accolades for whizbang features. It was interesting to watch them accomplish more with less computing power and a more primitive (IMO) development language (their Objective-C to our C#). Edit: I called it the "old-new" Windows app as there had been an even older app (predating C#) which the C# app replaced. In the circle of life the once-new C# app itself became ossified and stuck with whatever short-sighted design legacy decisions were baked in. There was a lot of technical debt in the codebase. I should say, partially replaced, as they were never (while I was there) able to convince all of the customers to upgrade from the original app built, hence why I say that big customers who can simply refuse to change might be a factor.