100%. And the UI is intuitive. If it looks like a button, it is. The scrollbar doesn't disappear randomly and actually is wide enough to grab easily.

Everything deteriorated once they went to the flat design. I need to find out which consultancy made the recommendation and everyone followed.

Flat design was welcomed by a lot of designers as it required far lesser skill compared to designers before the flat era. As a result it spread rapidly.

Thanks for the explanation, but why? Is drawing a proper button that hard comparing to a rectangle?

This might be a bit disingenuous. Another slightly less insulting yet equally valid interpretation is that design as a whole has shifted over the last decade plus to value form over function. The current unbridled minimalist aesthetic has a futuristic look attracts companies that want to look futuristic (Apple, Tesla, Microsoft…)

And for companies that aren’t leaders? Many of them want to be seen as such anyway, or at least not seen as irrelevant. (We might remember how X started popping up in all manner of names when XP came out.)

To some degree there is room for this as long as function remains a primary goal, however we might reasonably argue that the current competition in technology is to look sleek, not to actually empower end users, leading to a design language that’s main purpose is to look nice but not be ultimately useful.