Why TT Card Ceiling is 10?

It almost felt like a bug today. I nearly filed one until I remembered the stupid 10-point ceiling. I'll explain what I mean.

I was playing Garima at The Fringes (28, 20), where you get an interesting mix of both Plus and Ascension and then this happened:

https://i.imgur.com/nAxxqLA.png

AI moved to top-middle and abused the ceiling (top-right Thancred was +10 instead of +12) to make a Plus combo -- 5+10 right side, 7+8 bottom.

This 10-point artificial ceiling should be removed, as it allows for this kind of sleazy maneuver.