You could claim the same thing about JavaScript. It's very possibly more popular than Python, but it's definitely not better designed than Python or most of the other languages in current use.
The main difference with JS is that we don't know whether it would be so commonly used if it wasn't for browsers. Still, it seems that the majority of efforts are towards augmenting JS' capabilities rather than finding ways to use alternative languages on the web (yes, I'm aware of WASM and maybe in the long run this statement will be proven false).