You suggest that OW J pax do not get access to QF J Lounge because the capacity of the lounge is unable to accommodate OW J pax including at the time of my access request (though more accurately characterised as an access check). . I just ask the simple question - how do you know.?. You have been unable to point to anything that would confirm that. Maybe they were full at the time of my arrival but both you and I don't know that they actually were.
Incidentally, capacity constraints also apply to QF's own passengers.
My suggestion is that OW Lounge eligibility based on class of travel is less of a perk because of the catch all rule that allow a lounge to restrict access based on "capacity constraints". That is obviously reasonable on one level of analysis. but on another level, it could just be applied to OW partner airline passengers even though there is no capacity issues at the time of an access request.
They manage the lounge anyway they want - macro and micro - down to the type of hand towels it wishes to use. It is clearly not for any passenger to tell them what to do.
The outcome of their policies for me just means that OW class of travel perks might not be equivalent to the airline's class of travel perks in terms of lounge eligibility despite the OW marketing.
I also note that QF has distanced itself from OW lounge eligibility policies. There is no explicit mention of OW lounge access based on class of travel in QF lounge access policies.
And that's all OK. QF does what it wants to do.
I've only provided a data point for people to consider.