It would be lacking the isolation and anti-tracking stuff that Tor Browser does, so the level of anonymity that users would get would be much worse. But it seem

It would be lacking the isolation and anti-tracking stuff that Tor Browser does, so the level of anonymity that users would get would be much worse. But it seems like in your proposal the users aren't expecting to get anonymity, so they wouldn't necessarily object when they don't get it. Many clearnet sites would be extra-confused by seeing requests that are partially Tor and partially non-Tor (with subresources being requested from different locations). But the behavior isn't necessarily invalid in any way, so maybe sites should get used to it. :-) I think the performance hit would be pretty considerable if you think about the optimization that some sites, browsers, and CDNs have been doing. If you imagine users who choose browsers (or sites) based on perceived speed, they might not react that well to deliberately slowing down connections for privacy. (I think your idea is interesting.)