this is only partially correct because it does hurt privacy. the protocol works because all txns look nearly identical; a bunch of txns with bloated tx_extra fields do not look like the other txns. this makes it notably easier for firms like Chainalysis to perform passive blockchain analysis.
there's also the bloating due to spam, as you said.
Making the chain unusable is also harmful to privacy. Ultimately the Monero project, devs, and community are committed to the mission of private digital cash. If this gets in the way, it will be addressed. That being said, I think Monero is more insulated from this because we are less dogmatic about block size. Dynamic blocks arguably insulate Monero from this effect to a certain degree. If changes are needed they will be made. There are dogmas and taboos in Monero, but those are Proof of Work, the tail emission size, and privacy. I think those are generally well founded although personally I'm not as dogmatic about the tail emission size and I remain open, but not convinced of alternatives to Proof of Work.
Making the chain unusable is also harmful to privacy. Ultimately the Monero project, devs, and community are committed to the mission of private digital cash. If this gets in the way, it will be addressed. That being said, I think Monero is more insulated from this because we are less dogmatic about block size. Dynamic blocks arguably insulate Monero from this effect to a certain degree. If changes are needed they will be made. There are dogmas and taboos in Monero, but those are Proof of Work, the tail emission size, and privacy. I think those are generally well founded although personally I'm not as dogmatic about the tail emission size and I remain open, but not convinced of alternatives to Proof of Work.