Thank you for reading and for sharing your experience, Adam!
I think the difference may lie in the extent that we perceive allowances to be acceptable. For instance, as a Guesser by nature, even an Asker prefacing any statement by what you suggested 'It's totally ok to say no' already incorporates a tiny element of Guess in considering how the other person may potentially feel and giving them an out if they want it. Otherwise as an Asker you'd just ask straight out, right?
You're not wrong in saying it can be very difficult to deal with Guessers (this also holds true for Guessers who are not on the same wavelength and understanding as the other Guesser), and I largely agree that in many situations it probably is entirely easier for Guessers to be more direct.
But I would just temper that by saying that for many, that may be easier said than done (especially in certain cultures or for those dealing with intense social anxiety). It can indeed come across as near-abusive if it is intentionally weaponised by some types of individuals - but equally as often, it can just come from a genuine want to please all sides and an uncertainty of how to achieve that, as well as a fear of getting it wrong.
Assuming that we are trying to address the second type of situation (as the first is already intentionally malicious and so nothing here will help, as we aren't operating on the same premise any more), Askers can do a lot to help encourage that behaviour in the meantime by showing a little more overt empathy and consideration, as you have fairly suggested.