Falcon Heavy has 27 engines, Starship 33. Its not that different. And if anything Starship has a simpler engine configuration. This is not some unsolvable problem.
Falcon Heavy has 3 packs of 9 engines, each pack is thoroughly tested. They can treat the whole package as 3 sources of thrust, manipulating them as a one (which they actually do). Every booster has its own fuel tanks, lines and so on.
Also, I don't remember a single engine failure during Falcon Heavy launches. Today we had 8 (?) of them.
Falcon Heavy as complete system is still far more complex. You still need to coordinate all these cores. There is a reason every designer goes to single core as systems grow larger. SpaceX actually had initially planned to do a very large 3 core and then rejected it.
And Falcon Heavy was building on 10 years of Falcon 9 knowlage and an incredibly reliable engine.
Falcon Heavy was launching from a perfectly designed launch pad that didn't throw up huge chunks of debris everywhere.
Its incredibly that people are way to fast to jump to doomsday conclusion from one test.
