Lounges you get via credit cards, Priority Pass and similar schemes are, bar a few exceptions, usually very inferior to airline lounges. They also won't get you priority check-in or fast track, which are also important benefits.

Of course, none of it matters when you're flying in J. However, there's many people who fly J on longhaul but can't justify the pricetag on shorthaul. That is, as far as I'm concerned, the last remaining sweet spot of FFPs.