Here's the thing, they never were good developers, mediocre at best. Just look at what a broken mess Gen 1 is and keep in mind the international versions already had some bugs fixed from the Japanese versions. It's just, at least for me, the 3DS era takes the cake. The system already started to crap itself when more than two Pokemon were in battle, yet they thought it was a good idea to introduce hordes? Not to mention how utterly inefficient their decryption methods are and slow things down even further, according to dataminers. And that's not even going into how artificially bloated their file structure is, if we're taking them by word. For example, every cutscene in SM has a Lillie model, instead of having a global one that gets used for them all. Of course I haven't verified that myself, but I don't see a reason why they'd lie, as they have a reputation to uphold.
An always remember when Wi-Fi battles in, I think it was XY, sent data unencrypted, meaning people made software which tells you what move your opponent was going to do. Look up "Battle Analyer". It's been fixed by now, but still, WTH Game Freak.