I'm not sure why it's a concern that the whole file needs a rewrite.
Naiively perhaps I thought that was helpful with solid state storage because it means that old data is trimmed faster?
It mentions it near the entire file being in memory but that seems a dubious concern. If the key is in memory the entire file can be comprised either way. Nothing can really stop that if you have access to the programs memory.
It's an issue if you have a really big password database, for example because you are storing large attachments in there. Especially if you are also syncing the file over the network. Also if your file is multiple GB, having it all in memory is an issue because of the amount of memory used.
That isn't really how keepass is meant to be used, but apparently people do use it this way.
Naiively perhaps I thought that was helpful with solid state storage because it means that old data is trimmed faster?
It mentions it near the entire file being in memory but that seems a dubious concern. If the key is in memory the entire file can be comprised either way. Nothing can really stop that if you have access to the programs memory.