In Horizon 4, both Anna and Rivals are close to unusable at the endgame.
I mention Anna and Rivals together, because in Horizon 4, Rivals presented a list of hundreds of races, giving no way to know which events I had set times for. “My Rivals” was always empty, so who even knows what that was for.
Anna in the meantime offered to send me to races, she only uses proximity as a guide.
Getting her to instead route to races on the basis of the current car type, class, and preference/availability for rivals would both make Anna useful, and return interest to a popular Horizon 3 game mode.
The other thing that is seriously wrong with Rivals in Horizon 4 is, when using it from the menu, each time a race is complete the player is kicked out rather than back to the menu to choose a different race.
Rivals is definitely not unusable in FH4. It works pretty well, albeit there could be some really obvious tweaks to improve navigation. For example, it would be far preferable to be able to change car without exiting the Rivals event you are trying to do, rather than having to go all the way out, find a new car and start again.
We can certainly argue semantics, and a lot might depend on expectations.
My expectation is that games generally, and game modes such as Rivals in the Forza series specifically, deliver the most most value, are the most useful, when they are easy for players to use. Perhaps on PC this menu works better, on Console the main Rivals menu is 7 tabs over, then “Race Discipline Rivals” has 4 cards for “Road, Dirt, Cross Country, Drag”. For some reason “Street” is its own menu.
Road then (for example) has 25 tracks that you need to cycle between 1 at a time, each with 7 internal events for a grand total of 182 events. You can’t see any of the details of the events unless you actually open the track. Confusingly the button to see the leaderboard is “Change Rival”.
And, once you are done beating a rival, or setting a time, you don’t get returned to Rivals in the state you left it. You have to tab over, to rivals, tab over to the track, and see if the next class/track has a time to set.
Essentially unusable for all but the most casual, or persistent user.