I think the idea is that email scraper bots typically don't bother downloading images referenced by <img> tags.
But they will be as soon as this sees widespread use.
it won't be widespread imho, not when you share you email address with other parties that then lose/sell your details. fastmail like 'temporal' email addresses could help, however.
Querying DOM nodes is inherently more complicated than a regex on unparsed HTML.