This is what happens when one gobbles up whatever Microsoft throws over the fence... and it's clear they haven't learned their lesson because .NET core is on the list. There is no simpler, cleaner, alternative for them. By their nature such companies will (almost?) always end up in this situation.
Any developer working for them must now learn VB6, ASP.NET and Powershell and other great future-proof tech. That is, once again, not a great career move and certainly not an argument for learning many languages.
For the sake of discussion, that entire stack could probably have been kept to C++, Java, HTML5 and something for scripting assuming a talented engineering team.
C++ would have covered their Windows desktop needs from Windows 9x until today, including going cross-platform if needed.
Java would have covered cross-platform desktop apps and back-end, likely including whatever they're using golang for. Had they wanted more agility on the BE they could have gone with Python which doubles as scripting language.
HTML5 is self-explanatory. No need for fancy schmancy React or Angular which I bet they'll have to replace (or rather append to) in 5 years time.
So, TBH, my gut reaction to your comment is you might lack experience developing & shipping any large applications. That’s not an insult, and not a judgement; experience comes with time. Plus I don’t know your experience, I’m just letting you know what your comment leads me to assume. My only suggestion is to be a bit careful throwing around judgmental words like mess and useless and ‘not reasonable’ when you don’t know precisely what you’re talking about.
FWIW, this stack looks very normal even for a web-only application, and it looks simpler to me than the stacks & tech people use for shipping console games. Hell, I’ve written personal projects with tech stacks that have as many pieces.
If I’m off the mark about your experience level, you could make your case stronger by demonstrating that there’s a simpler cleaner alternative that solves the same problems, provides the same or better performance, build utility, maintainability, deployment, user experience, etc.. Do you have any suggestions?