My feeling is the "deep" vs "wide" thing is a circumstance of which groups you interact with (and also which facilities you have access to, and even to some extent the culture of your science community). Rubin is an example of what you can do when you build something massive specifically for a single purpose, and as more of these kind of facilities come online (SDSS and Gaia have been around for a while, but DESI, 4MOST and other similar facilities are coming, and let's not forget radio), it's what we get out of the whole suite supporting each other that gets the best science.