One of the key features of the mark of the beast is the inability to buy or sell goods without taking it. By way of vaccine passports, that already happened, so yeah that fear does have a foundation.
The only difference is the level at which people attempt to integrate the philosophy into their life -- I'm sure there is someone out there who has been impacted more by Terry Pratchett novels than the religion they were brought up as, and using either of those in the way the instigating poster did would be silly.
If you have evidence of people being unable to buy or sell goods without a vaccine passport, please share.
Oh, and do recall that the context from Revelation is that a person was completely excluded from the economy, not that they lost some privileges, so please don't waste time with false equivalences.
Although, honestly, it's probably a waste of time anyway: I just don't live in the same fantasy dimension as these people and their arguments hold no water to me.