I love making combat difficult for myself, so I use theater of the mind... for everything. I don't use any physical or digital tools either in-person or online.
I've run and played in games that use virtual tabletops (roll20, tabletop sim, foundry), and they all seem to work very well. However, I tend to focus mostly on the narrative and roleplay, so it feels good to do everything via imagination. It works out nicely, because I get to pay more attention to my player's faces and react accordingly. We also made our recent campaign into a podcast, so doing everything verbally helps us create a more cohesive narrative for listeners.
BUT I think theater of the mind works to my strengths as a DM, and it certainly isn't for everyone. I know I'm in a very minuscule minority, but you're welcome to join me at the theater table.