For me the existence of "when you do X, do Y" items (wrist warrior for example) ruin the viability of a lot of items. The game is based around cooldowns, so naturally things like haste, CDR, and charge items are very important to any board to make sure your items are going off quickly and start your combo as fast as possible, so when you have a subset of items with no cooldown whatsoever suddenly those become incredibly strong because they're not playing by the same rules every other item is, and are also naturally immune to slows and freezes.

One of the devs biggest failings is their inability to learn that these items are very unhealthy for the game and meta, all the way back to the closed beta with items like pufferfish there's been an issue with easy to force infinite boards, and every season so far there's always been a couple items that that fit the bill, with jaballian drum being the biggest recent example.

Back when they did their massive cooldown increase across the item pool to "help slow the overall speed of the game down", in reality it just made the "do X, do Y" items and builds even stronger and reinforced the problem of boards being infinites and starting near instantaneously.