The problem was the Microsoft zealotry of technical people they invent non existent problems often repeated like a cargocult by MS consultants/partners. They loved IE as a default browser. This has nothing todo with the apps being hard to fix, because that turned out to be an actual easy technical problem and I did 10 internal apps.

The only thing that helped was MS taking responsibility and killing IE. The problem I had was that IE was becoming an support burden on our tools, no customers were using IE but the internal staff was forced to.