1. tones, and generally the gatekeeping of some Cantonese communities towards people who haven't gotten the tones completely right
2. the lack of learning materials relative to the number of speakers, the confusion between written Chinese and written Cantonese (and also the general lack of the latter)
As they say, "a language is a dialect with an army and navy"... I'll leave it at that.
You seem to be confusing/overgeneralizing the understandable resentment of "some Cantonese" who likely had bad experiences of postcolonialism and/or authoritarian-revanchist state policies. If Hong Kong diaspora has a poor reception towards newcomers to their local microculture, maybe it's because the people attempting to engage are not treading lightly with those actual historical legacies in mind.
1. tones, and generally the gatekeeping of some Cantonese communities towards people who haven't gotten the tones completely right
2. the lack of learning materials relative to the number of speakers, the confusion between written Chinese and written Cantonese (and also the general lack of the latter)
As they say, "a language is a dialect with an army and navy"... I'll leave it at that.