Something like a Sans Amp is also a preamp that shapes your tone. If someone likes the sound, they could be using it for tone shaping and not for the DI functionality.
In a soapbox moment: I have a Sans Amp Bass Driver DI. I sold it, regretted it and when the opportunity arose, bought it back.
Having used it weekly for a year or more now, I've stopped using it. It sounds great when you're solo'd. Bedroom tone. But practically, it scoops mids quite a lot. In the end I pretty much had the blend to "no Sans Amp", so I just use the flat "pre-EQ" DI out of the head now.
Scooped mids make it difficult for you to really hear what you're playing, which leads to you turning up, which leads to volume complaints and/or running out of head room on your amp. You really have to respect the mids when you're trying to find your place in the mix. What sounds ugly on its own might be just the thing when the rest of the band is playing.
In a band you really have to get over your solo tone. It's pretty much irrelevant. I tend to keep everything flat, solo the neck pickup and pluck where the bridge pickup is or would be. It's up to you to find your own recipe, but that works for me more than 80% of the time.
So am I going to get rid of the Sans Amp BDDI? No. I own it and I think it has a fair amount of utility, if for no other reason than "when something else breaks".
KO