fasmw ide,

whenmode is on, you cant paste text.

vertical blocks pasted normaly.
vertical selection is not general purpose mode.
in some sources code have linenumbers, to cut them all in fastest way is vertical selection.
If thou going to change integer type for group of values from $-prefixed to h-postfixed or vice versa, or add trailing zeroes to all of that values - fastest way is vertical selection.
Or if all operands are tabbed at 8th position after instruction starts, thou can fast delete group of instructions and replace them by another group with same block size, or delete operands and replace them with block of operands, or comment group of lines within single operation or uncomment them.
Or let suppose thou making huge sequence of constant definitions, and thou start from defining column of its names, for pasting same vertical size column with equal sign followed by dummy value again vertical selection would be useful too.

In conclusion vertical selection is very useful mode for editing code, it can make things within couple of operations that in normal mode would require by 1 or more opertion per each line. But it can`t be used as general purpose mode because it have its own limitations.