Airline lounges are overcrowded and often not much nicer than the terminal. I, then Qantas Platinum, spent some time in American 'first'¹ lounges back in 2015-2020. What a shambles! So I understand why they'd want to limit the attendance.
I also had the misfortune to spend 6 hours in a BA lounge in Heathrow in 2022. Good lord. At least the gin was free.
Travelling ain't what it was.
¹Here in Australia there's no such thing as domestic First. We call that Business: if you want to travel First, you must go internationally.
At least during irregular operations, the staff at the lounge often have the ability to reschedule you onto flights or routings that regular staff can't (due to inexperience or due to privileges). If bad weather results in multiple cancellations, being able to walk up to the agents in the lounge and have them help get you onto a rescheduled flight is often very much worth it.
That's why the airlines started having separate lounges primarily for the Polaris, Delta One, and Flagship fliers. They are what the prior lounges used to be. Delta One at LHR is also nice because you check in at the counter and head to a special elevator and private security screening which dumps you out right at the lounge.
I also had the misfortune to spend 6 hours in a BA lounge in Heathrow in 2022. Good lord. At least the gin was free.
Travelling ain't what it was.
¹Here in Australia there's no such thing as domestic First. We call that Business: if you want to travel First, you must go internationally.