Blazor is not good at anything. Please stick with JS for the frontend .NET devs. You'll thank me later.
As old school as it may be, I can accomplish basically everything my users need with just vanilla JS and .fetch() requests.
I've been playing with Blazor, and it's been great so far. However, like everything, I know it's not perfect.
Blazor server uses websockets and is just a whole other bag of hurt. You'll have to deal with disconnects even if you can stomache the increased cloud costs.
You can (and I have) definitely rendered huge data grids efficiently with Blazor.
The biggest drawback with wasm is no proper multithreading support which has been delayed for years.
On blazor server; I totally agree, it's a pain. But for 'intranet' style apps which are used internally it's by far the most productive development environment I've used for web. I wouldn't use it for anything that wasn't a total MVP for public use but it's pretty great for internal apps like admin panels.