It's there (Business Limited Capacity), but it's scarce, particularly on North American segments.
I tried to redeem Canada-MCT for Thankgiving weekend (Nov), nothing from YYZ around the weekend, held one with "Pay and Fly" for YUL-IST-MCT. Just an hour before it expired I did a mock booking and there's no more Bus Limited, needless to say I pulled the trigger with miles even with a possibility of cancelling, can't beat the value of 47000 miles (NA to ME).
Perhaps it's a good thing now that TK has recovered and is doing well, so much so that they don't need to give away seats any more. OTOH it sucks trying to reap the benefits.