And to add to that, there are a bunch of sandhis, which are when the tones are shifted or modified when followed by certain other tones.

Using tones is so natural that many native Cantonese speakers are unaware that the language even has tones lol.

Your last point: I would say that is generally true for all native-level speakers of tonal languages. It is interesting to watch them try to learn a different tonal language. It suddenly opens all these doors into their own language. "Oh, so that's why foreigners struggle with this sound." Mandarin: zai, sai, cai

When you read about tonal languages online, there is so much emphasis on "tonal languages are special". I don't understand why accent and pitch isn't added to the same bucket. In Japanese, accent and pitch is rarely taught, but incredibly important in daily life. Japanese is stuffed full of homophones which makes listening a tricky matter. BTW -- I am sure there are other "non-tonal" languages that I don't know about where pitch and accent are important (Korean?).

If you consistently pronounce words with the wrong accent or pitch, (average, uptight) Japanese listeners will refuse to understand it. Say what you like about it (fake/real/whatever), it is a common response.

It even matters in Latin languages somewhat. Which syllable is stressed can change meaning, sometimes avoiding ambiguity.

Exactly. I use the example of different tones when saying “really.” It can have very different connotations depending on the tone from questioning to sarcastic.

Mandarin, Cantonese, etc. have per-syllable tones. English, German, French and probably many more, have per-partial-sentence tones.

Yeah, the seventh tone in Guangzhou Cantonese that’s gone in Hong Kong Cantonese is the high-falling tone.

In Guangzhou Cantonese, 衫 (shirt) and 三 (three) are not homophones, but they are in Hong Kong Cantonese. The Jyutping romanization (from the Linguistic Society of Hong Kong) reflects this change in HK Cantonese (saam1), whereas Yale, based on the older pronunciation, could represent the difference in tone (sāam vs sàam).

Interestingly enough, the high-falling tone is still retained in Hong Kong Cantonese for one exceedingly common word, the final particle 㖭 (tim1/tìm)!

I suspect the difference is more "academic" than otherwise.

It would be interesting to give a Hong-Konger a test with pairs of characters, one of 1st tone and the other 7th tone, and see whether they can guess which is which.

I suspect with minimal training they'd be able to score significantly better than random chance. (Willing to try it out!)

No need of test and I knew nothing. But I can be sure we hk Cantonese know and immediately hear if the other speak in canton or Malaysia Cantonese very quickly.