They have to.
It's uncharacteristic of OINP as well as lunatic to send NOI for 440's. I don't see their point ,as most probably ,candidates with that score would opt for direct-ITA any day. One cannot fathom the total number of registration against NOI's issued.
The only logical explanation I can conjure up is that, they have to start 2018 allocations but they have huge backlogs from 2017. Till re-opening of stream in November, OINP used to be the province which always sets a record having fast processing time which isn't the case lately. There are people from November still awaiting for nomination or change in status.
If they issue NOI's for 400's , it would eventually add up to the backlogs. Hence, they are controlling the intake by sending NOI to higher scores.
Am pretty sure, they will start issuing NOI's to lower 400's once they have cleared their pending files. One can only speculate, when they will start issuing, but from historical evidence, OINP and IRCC go hand-in-hand and there should be a very strong reason for CRS score set by both IRCC and OINP are alike.
"The OINP is managing the volume of applications to the HCP stream at this time. The OINP will be issuing NOIs on a regular basis to applicants, who at minimum, have a CRS of 400 and meet all eligibility criteria." -
Have a hope on this one