It could have been. Basically it comes down to the previous owner never putting in fresh fluid or filter.
Anytime the transmission does weird things like making noise or slipping. Damage has been done. From there it's only a matter of time. The faster a repair is made the better the chances for survival of the transmission. I have to ask myself, how long did the previous owner drive this vehicle with it whining. Had he done something about it, as you did, as soon as it started, you wouldn't be in this situation unfortunately.
The other thing that should be said is the transmission filter is not the only cleaning device in a transmission. There is a screen that filters in the valve body and one in the pump. When the fluid gets nasty looking, these can clog with fine debri.
I got one I'm rebuilding now. He just replaced his transmission in January from a local scrap yard. His began giving problems which he neglected. When he no longer could move with it, he finally tried to do something about it. It was way too late. Not only 3-4 clutches were burned out, but other components were broke too. It was still rebuildable, but the cost for the parts and the kit cost more then one from a scrap yard.
Fast forward to last week. He brings it to me and it's slipping when it shifts to third. Same way the other transmission began to act before it totally went.
I check the fluid level and it's 4 quarts low
It had an obvious leak underneath the vehicle. Fill it up and it's doing the same thing.
He still needs to get it home. I told him to put the shifter in second to lock it in that gear, so it won't upshift and try to use 3-4 clutch pack. Get it home and don't drive it again. Drive it easy with the fourways on. Keep your RPM's low. He listens this time.
We pull the transmission and find 3-4 clutch pack has gone bad. Nothing else.
The root of the problem. An aluminum piece that bolts the transmission to the transfer case had a crack in it. This is his third one, one being replaced by a dealer. The other being replaced when he did the transmission in January is what he tells me. I decide to look into why these are cracking. The root of it's failure came back to the same broken transmission mount he was still using. How this was missed is beyond me, especially through the dealer. I grabbed and wiggled the transmission and found it almost instantly.
The root of both transmission failures. Neglecting to check the fluid levels when you know you have a leak.
Had he just got underneath the vehicle to inspect the reason the first one broke, none of the problems would have happened.
A $20 transmission mount and fifteen minutes is all it would have took.