Not that I'd do this myself, but this isn't exclusive to Head-Fi. Mosey on over to speaker forums and you can see people blowing hundreds of dollars on CDPs then use them as transports; heck, dedicated transports with only digital outputs actually cost more, like this one:
That said some just use really good DACs and treat CDPs as relatively disposable due to the tendency of the transports to break sooner than anything else in an audio system, but of course they at least still go for a heavier unit than a cheap $100 Sony changer for less vibration.* One has to wonder if they're just used to having a TT (kind of like a CD transport, but the cartridge is a lot like having a DAC chip built into your laser head) with a separate phono preamp (essentially the output stage of a DAC, but in this case it's kind of like the DAC itself), or if some think that that's how all set-ups should be, with one specialized box doing one specific task - just read the "Schiit we'd like to see thread" for how many people, not even Schiit themselves, vehemently defend Schiit's previous comments on not combining a DAC and amp in the same box, despite the purpose of the thread as a way to test the waters for new products and people posting such ideas aren't even whining like what you'd see on non-Apple DAP threads.
If anything, I'm of the "even if they could, doesn't mean you always should" crowd. If I was already going to pay for and lug around a brick like that it better have a nice DAC and amp in it, and of course I would use a headphone or IEM matched for it for practicality. So yeah let 'em do that, but for people who might be asking if it's necessary at all, I'm one to say, "pick a headphone or IEM that won't need a separate amp from a player like that" (much less a balanced amp that needs a balanced output DAC too).
*I had the $150 SACD from them, and when I opened it up and ran it, the plastic arm holding the spindle and the CD was vibrating while the disc was spinning. I'm not kidding, you can literally see the CD making lateral movements while playing. Cheap POS. I put Blutac on spots on it that looked more like they were left hollowed out to save weight and it stopped vibrating. It read discs faster and more consistently after that.