The only reason they discontinued Spider-man was because they saw a special opportunity to partner with Marvel and potential to make Spider-man HUGE again through Marvel.
If that opportunity wasn't there I feel they would've just continued with TASM series. Having 3 true "Sony Spider-man" reboots in such a short amount of time would've been dumb.
Doing the "Marvel Spider-man" reboot didn't make it seem as ridiculous.
The Pact

It was a financial disappointment (I'm not even entirely sure it made back its budget, when marketing is taken into account), as well as the poor critical reception.
If you can't defend a movie without bashing another, you will be put on ignore. No exceptions.

Of course the promise of money is the motivator, but on top of that was the fact that they were going to partner with Marvel Studios and get Spidey in the already-in-place MCU rather than having their separate Sony universe.

Nancy Pelosi: "Tell 'em you're a Muslim. Tell 'em you're a Muslim."