Yes, vinyl is technically an inferior sound quality to FLACs. I'm happy to rant all day about the flaws of vinyl. I personally prefer high quality digital.
However on a good pressing there is an undeniable difference to a good vinyl pressing. It's not dissimilar from why I said that my kids frame the shots on digital cameras in ways that are different using an iphone. The processes that surround vinyl are different (better?) than those we use for digital mastering. Engineers pay more attention to vinyl mastering than they do digital. While there's a lot of shitty USB turntables, even those are often far better than how most people listen to music digitally which is often on iphones and shitty laptop speakers. The physicality of vinyl manufacturing incurs requisite different attention and processes that sometimes (emphasis on sometimes) results in a "better" listening experience.
Could you get the same "better" listening experience with lossless digital? Yes. but most don't. So vinyl is "better."