It is not false. You can't just drop two text files onto Kaleidoscope and perform a diff with manual edits. I do know that Kaleidoscope can support editing under certain specific conditions, but those aren't relevant for me. WinMerge supports editing under any conditions.

https://twitter.com/kaleidoscopeapp/status/34193087090041651...

That tweet is from 2013 and nothing has changed in the intervening nine years.