Most "modern bloated" SPAs are tiny. The default MSS for most TCP implementations is 1460 bytes, that's 1.42 kB max per packet. Just the TCP handshake packets themselves (3 * 1460) can hold almost as much data as it takes to get a standard SPA. This says nothing about the TLS handshake itself which adds another 3 packets to connection establishment. Most SPAs send small and receive small payloads; a compressed JSON exchange can easily fit in a single packet (1.42 kB.)
The actual amount of bandwidth on the wire between a server-side rendered "fast" app and a "modern bloated" SPA isn't very different, the difference is in how they send and receive data. SSR pages send a thin request (HTTP GET) and receive a large payload; generally the payload is much larger than the connection establishment overhead, so they make good use of their connection. On the other hand, a naive SPA will involve opening and closing tens or even hundreds of connections which will lead to a huge waste (6 packets per TLS+TCP connection) of overhead. QUIC makes it possible to have small connection-oriented request/response semantics on the internet with minimal fuss.
That said the problem with rants like GP's comment is that they don't serve to illuminate but serve to push on us, the readers, the author's agitated emotional state. Instead of having a discussion about bandwidth and connection overheads, or even trying to frame the discussion in terms of what "waste" really is, we get emotional content that begs us to either agree with an upvote or disagree with a downvote with nothing of substance to discuss. Any discussion website is only as strong as its weakest content and if content like this continues to get lots of upvotes shrug