would triple be better ?
Yes, bikes regularly use 7+ plates so they can minimise size.
BUT, it's a trade off. More parts to stick, more weight, thicker.
So a designer will make the tradeoffs.
Is it necessary ?
Not really, racing clutches have massive force and high friction materials so that they aren't as at risk and with flat-shifters are even under less stress than before.
So, now even a 2 plate is likely over kill
Torque convertors are horrible things in performance cars as they introduce a component the driver has no control over on how it delivers power.
To reduce wear on synchros all that has EVER been needed is to rev match the two parts as close as possible before the synchro engages. Flat shifters do this exceptionally well no. ( Friends manufacture and sell an excellent flat shifter for a number of pro sequential boxes and the difference in wear between a "best driver" and their module over a racing season is clearly visible ! )
Planetary could work, BUT is an excessively heavy arrangement for what it delivers.
Materials now make it possible, but heat generated could be difficult to dissipate.
Most CVTs are chains/chain like and PUSH rather than belts which pulled.
Wear a big issue as it relies 100% on friction to transmit the power as opposed to gears which are using levers.
From that link it looks like they will still require a flat-shifter type arrangement and the only advantage is it doesn't need a reverse movement of the synchro to engage, instead has a longer "stall time" while it engages in the next forward dog. Still need a clutch to get started
A modern racing box with good flat-shifting technology leaves a driver NEVER having to touch a clutch pedal other than for first launch. These are used in all successful sprint and hillclimb race cars in UK where acceleration is most important ( and less weight ). If you search youtube for any of the bike engine hillclimb cars you will hardly hear the engine hiccup while it blips for up and down changes
"A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'