You can't look at some site that has 10MB of third party deps and compare that to what Blazor is doing. You'll still need third party deps with Blazor as well.
The sites that have a large 10MB bundle would have had 100's of 100KB scripts pre-spa days.
I suspect you're talking about full apps that include third party deps. The majority of SPAs are < 1MB unzipped and <150KB zipped. Source:
https://gist.github.com/Restuta/cda69e50a853aa64912d
You can't look at some site that has 10MB of third party deps and compare that to what Blazor is doing. You'll still need third party deps with Blazor as well.
The sites that have a large 10MB bundle would have had 100's of 100KB scripts pre-spa days.