3.5/PF1 have an open and usable gaming license that allows for plenty of community creative content and support. GSL for 4e is too prohibitive to allow anyone license or distribution of a usable system for any vtt, but it's not for a lack of want. WotC scorched the earth when they tossed aside 4e and its fans.
In defense of:
"WotC scorched the earth when they tossed aside 4e and its fans."
They were compelled to.
WotC had already made an own goal of epic proportions with the switch to 4e.
PF1 showed that 3.5 still had legs for a good 4-5 more years. Give or take.
They had alienated part of the fanbase with the way they rolled 4e out, and continued to run into various issues early on. Which when taken all together, ensured that for various reasons; 4e was just not a very well received edition of D&D.
The proof in the pudding was the fact that 4e got outsold
on merit, by a clone of the previous edition.
Yes, it happened...
D&D, the all singing, all dancing, market leading mother of RPGs, got outsold by a clone of its previous edition.
For Ha$bro/WotC, this was an unacceptable situation.
Unacceptable. Period.
Whatever merits 4e had as a system were made irrelevant when Pathfinder took over the number one spot.
Good, bad, didn't matter. 4e was divisive for the D&D fanbase. Yes it had fans, but
not enough fans!
It had to go.
So house was cleaned, heads rolled at WotC, and Mike Mearls herded cats on keyboards until 5e popped out the other side.
And we continue to see the proof today that WotC made the correct decision
for D&D.
As soon as WotC gave D&D fans a reason to come back into the fold of "Official D&D"; they did.
PF got put firmly back into the number two spot almost immediately, and 5e has been putting all things Pazio way way back in their rear view ever since...
PF1e doubling PF2e...wonder why? Probably has to do with the fact there wasn't a real demand for it and PF1e was doing just great,
then Paizo tossed it aside for PF2e like it was the best thing ever to come to gaming. Bad idea to have their fanbase split apart, they could've gone strong with PF1e but I guess that's the point of a venturing risk...it's a risk for probably success or failure.
And in Pazio's defense of:
"...then Paizo tossed it aside for PF2e like it was the best thing ever to come to gaming."
They had to do something.
Pathfinder 1 took the number one RPG spot from 4e on merit. But once 5e came out Paizo began to hemorrhage market share back to WotC like a bleeding swimmer at a shark frenzy.
By Pazio's own admission they never fixed the underlying math issues with 3.5. The Pathfinder rules were essentially an employees house rules laid on top of the OGL. Whether you want to admit it or not, the roaring success of 5e has shown that 3.x D&D had reached the end of its edition life cycle...
So Pazio had to do something to generate excitement for its brand and try and reclaim some of the paying customers lost to 5e.
(IMHO Pazio was just trying to stop the bleeding, and even they had no notions about ever being the number one fantasy RPG anymore.)
Personally, I think that they waited too long, (almost 5 years from 5e's launch), and went in the wrong design direction. But it is easy to backseat drive with 20/20 hindsight, and tell other people what they should have done with their money.
While one can quibble that roll20 is not accurate for PF2 because it is better supported on other platforms, but given that the subject has been discussed at length on other threads, I don't feel I am being controversial at all when I state that I don't think PF2 was quite the success that Paizo was hoping for.
Regardless, the end result is largely as you mentioned; Paizo has essentially split their fanbase.