To me, playing is playing clear notes at the right time in the right order. I'm sure some will balk at this. So be it.
The only thing is that if you use certain techniques to play certain notes or chords, it may limit you in terms of speed or accuracy. Using your thumb means orbiting the neck using the arc of your hand (area between thumb and index). This extra movement adds strain to the wrist, takes time, and to shift to another chord you've another large movement that takes time.
If you can play the songs you want to play and play, say, D, by barring with your thumb, then all the power to you. You're playing the song. The timing is spot on. It sounds good. It's music!
I know, though, that the songs I enjoy playing (almost all involve finger picking and sliding from the first to the 10th or 14th fret) require more left hand mobility than beginner strumming-only tunes that only involve the first four frets... so I forced myself to acquire more agile finger positions. Was painful. Took time. My neighbours hate me as my uke sounded like a molested rodent for weeks. But I got there.