Because you heard it from a bloke down the local pub? Alfa use the same suppliers as the other major automotive manufacturers. Are you saying that Bosch electronics on cars made by Alfa Romeo can't be as reliable as Bosch electronics in a Mercedes for instance?
What an odd stance to take.
If you want a mega mileage Alfa just go out and buy one.
You don't need me to validate your reasoning surely, or perhaps you do?
When you've been an Alfa owner as long as I have, the only conversations down the pub about them are started by me, and that's usually about the style they ooze rather than the mediocre mechanicals.
Only you've mentioned electronics, it did used to be an issue decades ago, but never for me.
Far too early failure of cambelts / water pumps on certain models resulted in many cars being binned - that was a huge problem.
Cam chains have been an issue on some later models, not to mention not fit for purpose gearboxes, all thanks to GM of course.
Even new models have had well documented problems with Multi-air units.
I think if most people got 200k out of a petrol car by any manufacturer, they'd be more than happy.
I know I would.
Much more and you're playing with fire, particularly if you're reliant on it for much of a distance.
I guess I'm not much of a gambling man