UT99 and all the Unreal games have been delisted from stores and they're shutting down the game's master server. You can still play solo or in LAN but online multiplayer is gone and there's no (legal) way to get new copies.
as someone who has played so much of these two games: both are incredible games, in their own way - creating/testing maps, the weapons, the movements, the game-modes, the moddability (skins, sounds, etc)...so good
Because to make the next Fortnite takes not just a lot of money, but luck. What if they made a game and it flopped (a techinically impressive game can definitely flop)? People will be like "oh see Unity engine is so bad, even the game from the first party doesn't sell".
In some ways this is backwards, you could argue Fortnite was a flop and became a success because of their license conditions (pivot to cloning licensee PUBG).
Unreal has had much more favourable license terms since ue4 in 2014, which is before Fortnite and the Store. To the best of my knowledge, unreals terms have always been "good", which is one of the reasons it's so popular.
The only reason Unreal engine has so favorable license conditions is because Epic Games earn billions from Fortnite and Epic Games Store.