I would agree that is one goal. Tho ADRs did that. But then you had ADR-abusers (go on lash out at me!

) You know ppl who would book 10 ADRs in a day then show up to 1, not caring that 9 other ppl didn't get to make a ressie cuz they knew they could block out 10. So Disney is closing that loophole... but getting back to your point...
I would say aside from FURTHER locking in the park (combined with ADRs) the FP+ has other benefits...
Make ppl less likely to retain unwanted ADRs... cuz now you are locking in your FP picks, you will not need those alternate ADRs as backups.
And most importantly, get
the bulk of their visitors a good experience, on 3 rides, on a few more standby, then off and drinking and shopping.. instead of those potential shoppers waiting in line cuz they didn't know they should split up their family and go run for FP tickets right away.
It was not very intuitive before. The concept of FP running is an "optimization strategy" that only a few learn... (myself included, remember, I was an FP- master too). But it is not "normal vacationing" for the bulk of visitors spending the bulk of money.
It just comes down to money. Does Disney listen? Yes. Unfortunately ride-optimizers are only marginally profitable, compared to say that casual vacationer. It's just the reality of life. Don't believe me? Well... Disney seems to agree so I can't really be too off base. I'm not the one saying Disney is going to implode cuz they are offending some ride-optimizer customers.
I am a ride optimizer myself... yet I can look past what I'm not getting - and see the bigger picture here and observe the benefits. Doesn't mean I like it. Doesn't mean I dislike it. But I am smart enough to step back, nod my head, and say:
"Well done, Disney. This is why you are #1. I'll have to give some thought as to how to redo my Disney touring."