I could be wrong, but the 10-year abatements started in 1997-98 and were limited in scope by geography and type of development. Due to the success of that small change, the scope was enhanced further in subsequent years.
And indeed, your 10-year tax abatement starts when you first renovate/rehab the property. The first buyers take advantage of it and the clock starts ticking...so there may be many properties on the market now that took advantage of the abatement in 1997-98 and their 10 years ran out a couple years ago.
But someone like shosh or others with more knowledge can correct me and explain it much better.
"The only difference between the Republican and Democratic parties is the velocities with which their knees hit the floor when corporations knock on their door. That's the only difference."
- Ralph Nader