Source: I'm colorblind(protanope) and red would definitely be an issue. Android studio, for example, is really annoying for me because the particular red they use for errors is very hard to distinguish from black
Especially in this case, where there is unlikely to be a specialized class of scammers who go phishing only for people with red-green colorblindness. So long as browsers implement a feature that stops the phishing in 99% of cases, the scammers will try something else.
Compare to Chrome's https indicator- it turns the "https://" part of the URL green (which I can barely distinguish as different, so it is useless to me) and adds a padlock icon.
Colorblind-friendly graphs might use both color and symbols to distinguish elements.
Significantly less common than red/green deficiency, though - I only know of one more on the island I live on (pop. 15,000 or so)
