Brand Explorer is not a past promo; it's still one of the benefits of the WoH program. I think many find the 5 brands relatively easy to get. I recall it took me less than 2 months to get the 1st free night, and I got to 9 brands soon after. I've been "stuck" there since the summer of 2017. Given the free night is a "once in a lifetime" for each set of 5 brands, I haven't been in a hurry to get to the 10th. Maybe it will be easier with Hyatt's recent acquisitions ...
I just realized I might hit LTG without getting the 5 brands.