They are glitchy
In what sense, what does this even mean?
they are slow
.NET Core is one of the most fastest tech stacks. Java is also very, very fast - it's JIT compiler can even remember "if" statement logic and skip it completely in some cases.
they are platform dependant
Both Java and .NET (Since 3 years or so) are not platform dependant. Bonus: .NET is also open-source under MIT.
they are full of legacy
Nothing to do with tech stacks, there are a lot of Ruby and Express.js legacy code right now as well.
all the tools are damn awkward
I'm pretty sure IntelliJ, vscode and even VS2016+ are not awkward.
Sorry to bring it to you but you have no idea what you are talking about.