One key difference is that those celebrities of old were famous for things quite disconnected from the thing they endorsed. And even when it was close (athletes

One key difference is that those celebrities of old were famous for things quite disconnected from the thing they endorsed. And even when it was close (athletes endorsing sports gear, Hollywood beauties endorsing hair products) the "they are getting paid for the endorsement" was still nicely disconnected from what they were faimous for. Most influencers are famous for voicing an opinion on stuff. The stuff they are paid to praise. This seems as if it must be even more obvious, with the fame and the business so well aligned, but somehow this alignment appears to enable the fame to outshine the paid nature, like a person standing between a car's headlights would be perfectly invisible despite getting quite some scatter light on them. When the endorsement is orthogonal to the fame, perceiving it as what it is turns out to be much easier.