I don't totally agree about its strengths not being relevant. Memory safety is an extremely low bar that the web has generally managed to meet, but Rust has a lot of value elsewhere. The author talks about significant performance improvements, which would be very welcome on many sites, as well as improved error handling and data validation patterns.
Most things thank goodness are not SPAs, nor do they have to be.
The problem here is the concept of SPA itself - it's a complete hack which is plastered over with various tricks to make it halfway usable. This has been going on for years now.
Websites on the other hand are slow because of the tracking and the ads which load tons of JS. Remove that and the web will be blazing fast.
If you have A LOT of content (eg. a table with 10000 rows containing rich data) it will be faster to use a JS virtualized list than to just have all those 100k+ DOM elements computed at once.
