The other answers are correct, but there's a historical factor that hasn't been mentioned.
When I started to search for do and donts and tips I realized that a lot of projects use PHP and I have actually not found any PBBG using C# which I find really strange.
Until a couple years ago, there was a PBBG development community that mostly existed on two forums: BBGameZone and MakeWebGames, both predominately filled with PHP programmers. Newcommers who didn't know how to make a game were pointed over to the awesome tutorials at BuildingBrowserGames.com which was all in PHP. The "PBBG" term comes mostly from games made by folks connected to these two forums, there was an effort to popularize the term so that the genre would have a recognizable name that players could search for and hopefully slow down the decline of the genre, it's no wonder if you're only getting PHP when you search the term.
It seems as the stack Im working with (C#, MSSQL, Angular) could suit a PBBG.
The only reason I can think of C# not being used is the hefty price of Visual Studio and the fact that it wasn't open source.
I think you're 100% fine to go ahead with using C#, MSSQL and Angular. You'll find that most of the PHP engines are outdated PHP4 or PHP5.
The BBGameZone folks were mostly against using engines (everyone was writing their own engine, including me) There was an effort by the MakeWebGames people to get new PHP engines in place (McCodes being their main old engine and NWE (New Worlds Engine) being regarded as the probable new one that was half-way done)
Here's a Google doc with an engine comparison from a few years ago, comparing McCode / NWE / ezRPG / GL Script: https://docs.google.com/spreadsheets/d/1WM3axFhYaAtjiKd1KRwibx9jEegwjwCJNhQmXP_jzss/pub?single=true&gid=0&output=html
There have been past efforts to put the old community back together, but not much luck so far:
I think you'll be 100% OK going forward using a C#, MSSQL, Angular stack, just remember that you're probably the first person writing a PBBG with your toolchain and you'll have to create everything yourself without any past examples to look back on.
Just remember that the genre is dying right now, but all it needs is one or two popular games to revive itself, if you think you can do that in C# I'll be rooting for you.