Enough happened in those years that we have the outline for those 3000 years. So we then have enough to infill. And it will probably end up being glorious.
I mean, a lot of the vague outline of events in question, happened over the course of decades from each other.
This isn't no fudging how long Frodo had the Ring. This is the Second Age being a few hundred years long, simply so a series would actually have more then one or two "canon" things to even DO.
It's not that it is impossible for the series to be good. It's just... With them basically having to start from the ground up as far as the story goes, I wouldn't get your hopes too high.