To me they're two completely different things. Using groups was made easier in recent versions since it defaults now to unnamed and can be made with a single click no input needed.
I use both extensively, groups are much simpler & quicker to use but are no substitute for blocks.
Grouping a selection of objects makes them easy to copy or modify anytime you wish. You can toggle group selection on/off with Ctrl+H to edit or remove individual objects.
I've even added a macro for inserting objects from another drawing as a group so they're easily editable.
Code:
^C^C_pasteblock;\(setq LstBlk(vla-get-Name (vlax-ename->vla-object (entlast))));_explode;_last;_-group;_create;*;;_previous;;(command "-purge" "B" LstBlk "N")
(setq LstBlk nil)
You lose all of a drawings groups when they're inserted into other drawings as they're not actually objects like blocks are and don't have all the power or abilities of blocks.
I don't see it as one or the other and would never discourage using either in general.
Making it company policy to use blocks in certain situations sounds fine if that helps workflow though assuming layer standards were already in place wouldn't selecting all the common property lines with Quick Select or Select Similar be easy enough not to need either method?