I see your point and that is in my mind really the only selling points for the dedicated cue lathes, they are easy to move around. I just spent a few days assembeling a engine hoist and moving my lathe around, it takes time and reqiures some muscle...
Taig based lathes is versatile up to a point. Just parting or turning down some G10 material is at the limit of what the lathe can handle.
I do metalwork for a local cabinet maker, so I need the metal capability.
So I stand by my initial post, with the caveat, that you need more space and dedicated equipment to move your stuff around.
Parting G10 is something 99%+ cue makers will never do. Metal work is rare, too, with most cues. Aside from shaving a stainless joint collar, it's rare that I need to do anything metal. If I had the need, then I'd certainly have a machine capable of the task. Otherwise, for cues, I find zero need for a large metal lathe. I do have a small one that I use for threading ferrule tenons, but that's all it is used for these days. I initially bought it for making joint pins, which I did for several years until contracting them out.
As for versatility, there are cue specific things I do with Taig based jigs & machines that would never be viable on a machine lathe. On my deluxe lathe alone, I can SIMULTANEOUSLY set a jig up for making dash ring billets, a jig for parting rings off said billets, and point/butterfly recut jig. All three stations can fit the one bed at the same time, and if I had six hands could operate all three simultaneously. I use that single bed as a station for coring, facing, ring parting, point cutting, fly cutting, etc. I have several carriages & top slides equipped with different tooling, a few head stocks for various jigs, a few tail stocks, and a few other beds. If so inclined, one can be equipped with a panto, or fitted with CNC. None of it is permanent and nothing requires extensive modification. In terms of versatility as it relates to cue making, I fail to see how a machine lathe can compare.