Which would be an insanely expensive way to collect very little usable information. Mirrors are run for free by volunteers, a worldwide CDN to replace free mirrors would be prohibitively costly for a relatively small distro like Manjaro.
Redirecting the requests to the closest existing mirror also obviously drastically reduces bandwidth requirements and should presumably be doable with a few (for redundancy) colocated dedicated servers running efficient server software.
I agree with the core point that tracking users via package updates is a bad idea, but I don't think this specific argument is very great.