yes, that has always been the case with any RPG-Maker (and is one of the reason why the earlier makers were re-released, not because there are many who use them but to get the licence for their resources).
If a maker has a different format you'll have to change the resources yourself (like resizing 150% on Ace resources to be used in MV/MZ), but as long as you own every maker involved you can mix and match their resources.