Bitcoin is fundamentally a market for block space, and out of band deals are part of that market. It isn't a new phenonema, I remember people complaining about this as far back as 2011.

The mempool is the most popular mechanism to bid for block space, but the market routinely experiments with other mechanisms and that's a good thing.

When reasoning about these types of issues, it's important to understand the security model: people who are infatuated with JPEGs aren't the adversary, the State is.

The "final boss" level of State attack is a hash war: the State will attempt to make Bitcoin useless by mining *empty* blocks. The only defence against this attack is to out-hash (out-spend) the adversary.

The more valuable block space is to the market, the more the market can spend to out-hash the adversary.