Overall, monobaths are good for two main things: they make a really easy first-timer entrance into processing B&W negatives, and they support minimalist (say, for travel) in-the-field processing, which can eliminate the need to carry exposed film through multiple airport security checks -- after all, X-rays at reasonable power levels (below where the film base melts) have no effect on developed film. The old classic photojournalist trick was to develop 35 mm film, still in the cassette, in a water glass, with a monobath.
As such, it was always a niche market -- people who needed to develop on the go. With the offerings available today from FF and Cinestill, it's become an easy, simple entrance into shooting and processing film (film is easy to get, but finding places to process your B&W is an issue if you don't live in a major city, and even if you do, it'll cost you a mint). Buy a jug of Df96 or FF No. 5, a daylight tank, and a changing bag, and it'll cost you about as much as having a send-out lab process two rolls of negatives, and you can see your images in less than an hour after shooting (instead of a week or more to mail the film out). With one jug of chemical.
From what I've seen online, the shadow detail in Df96 processed negs looks good, and I can fix contrast in printing, within reason (sure, I'd rather have my negs print on Grade 2 to 2 1/2, but a printable negative in hand is better than a perfect one coming in the mail in a couple weeks, provided the USPS didn't choose my package to the lab for an X-ray).
My darkroom isn't really set up yet, but I have daylight tanks, changing bag and a way to hang the film, so I can at least process my B&W negatives -- and a monobath works better with limited working space and equipment, at least until I see results that say otherwise (and apparently Foma 100 and 400 are on their list as "no special treatment needed, box speed"),