1.2.3.4 is very different from 8.8.8.8 and 4.4.2.2, etc. In the case of the former, random advertisements leaking from whoever are expected and normal. They should be blocked, but the concept of should in the global routing table is an amusing one at best. In the latter case, the routes are expected to come from known origin ASNs and a misalignment would be rapidly and easily detected, especially one for malicious intent or fraudulent purposes.
Never underestimate the willingness of a malefactor to subject hosts he controls (but probably doesn't own) or even hosts he doesn't necessarily control to vast quantities of traffic.
There are no advantages to this proposal and substantial danger, actually. I support dropping it.
Owen