Even if you have a valid point, modern fingerprinting technics usually is done through your data and the connection dependencies of them (which accounts are activated from the sane computer and so on).

Selfhosting remove some links between your data set like the files you store in drive, the people who appear in your photos, your contact list, to whom you email… Etc etc

Suddenly all this data is vanishing from the big techs, so, in theory it would be possible to make that association process more difficult