I do it the "olden ways": Place a link to the Sims3 launcher on your desktop, Click that link to start said launcher. Clicking the link will, of course, start the EA app first, but most times, it will shortly blink up, then disappear to the background while the Sims3 launcher will finish loading.
This won't work if the EA app decides it has to do something, like update the EA app or see a new login from you, which "forgets" about loading the game. In that case, just click your desktop link a second time after the EA app is done. However, this is rare. In most cases, it just works like with Origin.
As for "what EA expects"? Games are subscriptions nowadays. Looks like Sims 5 will follow the "games as a service" model. You're not supposed to play any games you won't constantly pay any money on. This "bright future" has already arrived for many franchises, and the EA app is built around this. I remember when Sims 3 failed to load because the EA app felt the need to remind me that my EA Play subscription had run out. That I still have games I don't need a subscription for seemed to be like an afterthought. At least, for the time being, that particular issue has been fixed.
Edit: I forgot to mention your graphics issues. I doubt those have any relation to the EA app, as the EA app technically doesn't run your game; it just checks whether you have the rights to run the game. Usually, issues like that are due to graphics drivers updates (Nvidia, AMD, etc). You may have to remind the Sims3 of what graphics card you use and check whether the fps restrictions still work (the ingame setting never worked).
