Any idea what's different about the mechanisms that creates that problem?
The reason exchanges have to turn off Ethereum time and time again is probably just shoddy code. The software doesn't really behave well under load.
But the reason scaling is problematic is the nature of the scripting engine. It's supposed to do everything for everone, so the number of corner cases with exponential validation is unknown. The transaction fee system on top of that is centrally managed, not in theory but in practice. That doesn't adapt fast enough for rapid load changes.
When I peruse a forum on it I feel like your old auntie looking at a Bitcoin forum because she has to pay her revenge porn ransom.
Oh dear, the images in my head.