You've probably turned up to a BJJ gym one day and seen some grizzled old brown belt absolutely covering himself in finger tape. What's he doing? Why is he doing that to his fingers? Is it just a flex?
If you're a gi guy or a judo guy, you've probably had your fingers absolutely smashed at least once while sparring. Gi jiu jitsu is very grip heavy and hard on your fingers.
Personally, as a hobbyist Brazilian Jiu Jitsu purple belt who uses a keyboard for a living, I use finger tape as a preventative tool. I use the cross wrapping strategy and protect my fingers from being bent in weird directions with the tape.
Other people who already have injuries will tape 2 fingers together as a splint to prevent movement.
You can also be a little bit sneaky and use finger tape to enhance the grip on your fingers due to its sticky nature.
At the end of the day, longevity is the key to jiu jitsu. If you're waking up with sore fingers after training, then finger tape could be something to consider.