If you select
1. save as csv
2. edit the filter
3. select a text delimiter e.g. "
4. select Quote all Text Cells
5. and a column only contains numbers
the delimited will not be applied. So, literally, it's doing what it's saying: Only enclosing text cells.
However, it should be possible to just enclose all cells with delimiters
Operating System: Mac OS X
Version: 184.108.40.206 release
Confirmed. Only fields of Type text are currently enclosed by the text delimiter when the "Quote all text cells" option is selected. Seems a reasonable request. Status set to NEW. Summary amended for clarity. Severity set to enhancement. I tested this under MacOS using v220.127.116.11 and GNU/Linux using v18.104.22.168 and in both cases the behaviour is as described. It has likely always been this way. Platform set to All/All.