I don't know how you got those results..

for me, "incent" gets 461,000
"incent -incentivize" gets 460,000

which means there are 1000 pages which have both words

"incentivize" gets 242,000
"incentivize -incent" gets 239,000
so there are 3000 pages which have both words

at least these numbers are somewhat in the same galaxy.