Acolyte of Zothique
Adventurer
That's your experience, it wasn't mine. We discovered class, prestige class and spell combinations that were rampantly broken. High level Psions with Astral constructs and Druids who could cast spells while wild shaped with Giant Animal companions were the straw that broke the camel's back.I ran and played in a dozen or more 3.5 games that ran to 14th-22nd level. It was over powered, but as long as the DM knew the PCs strengths and weaknesses, it wasn't all that hard to challenge them with encounters. I didn't find the game broken at all. Some individual spells or feats, sure. The game as a whole, no.
The players discovered broken high level aspects to the game and - as the DM - so did I. Our games degenerated into an overpowered arms race.
I'm glad that some people managed high level 3.5 games - I'm not sure how though. DMing high level 3.5 was a nightmare due to the myriad of abilities and feats to keep track of. 3.5 was poorly designed for high level play and I'm not certain it was really playtested. Throw in material from the myriad of sourcebooks - the combinations of which could not possibly have been playtested - and you have an unholy mess.
The only way 3.5 was playable at high level was if you stuck strictly to core book material; we didn't so I'm very grateful that 5e has reigned in the splat bloat.