Unsurprisingly, the companies you listed churn out some pretty terrible code. Square Enix for example has pretty big problems with ffxiv because hacking and botting is so easy. Maintenance windows have gotten longer and are occurring more often in an effort to patch vulnerabilities. Just last week players who were in a specific city accessing their retainers (personal bankers) had their money flushed from their characters by hackers who compromised the trade cluster and transfered it to their bots by listing bogus trash items for millions of gold.