In "Common mistakes" this article first says not to add this record if you're not actually planning to sell the domain, then says that the record doesn't oblige anyone to do anything, that feels quite weird to me.
TLDs like .online actually have a registrar-based dynamic pricing system based on internal rules, like domain size, presence in word lists, plurality, etc... And their distribution of available to taken names is quite good. It's different, which is already good, no one needs yet another TLD with the uncreative allocation system of copying the .com, we need variety, and I feel a binding DNS based offer system might make for a aftermarket-based continuation of the successful .online experiment.
But if the offer is not binding, then it's just an advertisement, no consideration, no contract, unlikely to amount to anything materially different than a 'domain for sale' HTML pages. In fact, if the HTML page has a buy now button, it's effectively an offer that can be accepted just by clicking the buttons and inputting cc info, so it's even better than a non binding DNS record.
Also, let's stop using TXT for everyone, why is everyone such a pussy about actually using record types? Do we really need every tool to be compliant out of the box? What's wrong with forcing vendors that want to be compliant to actually write like 20 lines of code and formally implementing support for the feature?
Around 1998 I registered a domain. Sony registered a trademark with the same name a few years after that. Someone on a Gmail account asked if he could buy it - I later found out he worked for Sony. I told him no - it's for a game I've been working on. I went on a vacation for a month and when I got back there was a fedex package filled with documents from Sony saying I'm violating their trademark and they'll take the domain.
I got a lawyer and he told me that I shouldn't offer it for sale as that would show the arbitration board that I don't need the domain. But he also told me that in order to fight the trademark it would probably cost a couple of hundred thousand dollars. So I could keep the domain but not use it for commerce...
In the end I ended up selling it to Sony but through my lawyer - I never stated it was for sale. But this was early on for domains and I wonder what the process is like now.