You're suggesting to load a whole new parser, parse images at a higher level than browsers can (i.e. slower and with less concurrency), and make `<img>` a whole lot harder to manage.
That's not worth it at all unless the savings are substantial (say BMP vs JPEG)
Performance is not a factor in this.
> Performance is not a factor in this.
If you care about SEO, it does. Check Google's pagespeed test.
edit: Case in point, except for google.com (which itself has a terrible score of 62) I can't even find out a single google service that isn't in the reds on the pagespeed index.
Even when it decided to load the mobile version.
What a completely ridiculous statement. Why else would anyone choose BGP if not for performance (i.e. download speed)? The choice to use BGP over a plain old JPG would be made specifically by people who do care.