My biggest beef with LibreOffice's spreadsheet (and with Apple's Numbers) is how they handle copy/paste of discontiguous selections.
Consider this 5 row by 3 column set of data:
1 2 3
4 5 6
7 8 9
a b c
d e f
Suppose you select the 1 2 3 row, the 7 8 9 row, and the a b c row, copy them, and paste just below the d e f row. In Excel you get this (first 4 rows omitted for brevity): d e f
1 2 3
7 8 9
a b c
In LibreOffice and Numbers you get this (empty cells denoted by "-"): d e f
1 2 3
- - -
7 8 9
a b c
I haven't found a setting to change this. Excel doesn't have a setting for this either as far as I know, so people who do want discontiguous copy/paste to preserve spacing would probably be as irked by Excel as I am by LibreOffice and Numbers. But I don't think I've ever actually wanted the spacing preserved so it is LibreOffice and Numbers that irk me.