He seemed to be talking about combat which is why I restricted my comment to talking about combat.
Well, it really is all linked together. As I mentioned before, Clerics had exactly one direct damage spell by the time they were 8th level in AD&D. It's not like they were casting in combat obviously. Even Druids only have 2 by the time they get 3rd level spells and one of those took 10 MINUTES to cast. Again, for a large chunk of their time, they weren't casting in combat.
After all, nothing quite says druid or cleric like a dude hurling balls of fire every single round of combat. Which is what we get in 5e - either Produce Flame for Druids or (grr, name of spell escapes me and I'm too lazy to get off this couch to look up the name for the cleric one). Or, better yet, our handy dandy bard dropping fire bolts every round as well. That's certainly in keeping with bardic archetypes no?
IOW, there's virtually no reason why all full casters aren't dropping combat spells every round. Outside of combat, they still have more spells that they can be dropping multiple times. Any caster with Guidance effectively has proficiency in every single skill. More or less. After all, it just takes one round to cast Guidance and poof, +1-4 on that check, pretty close to proficiency bonus. Oh, and the added bonus of it actually stacking with proficiencies.
In our current group, our scout gets sent out after the
druid turns him Invisible. Because, y'know, invisibility is a totally druidic thing to be doing. ((Note, Circle of Land Druid with ... Grassland? focus))
The classes are dropping spells pretty much every single encounter - either combat or non-combat. There's extremely few situations that come up that the classes aren't dropping spells of one shape or form. It would be fine, IMO, if it were one or the other. Clerics and druids typically did a lot of casting outside of combat - information gathering stuff, talking to animals, healing, that sort of thing. But, now? A druid is pretty much just a themed wizard. What distinguishes a bard from a wizard? Armour? Weapon? They barely need to use either one. Between Shield spells and decent HD, a wizard's just as good in the front lines as a bard. Other than some minor variations, all the core casters, save maybe the warlock, are virtually indistinguishable. Same spells, same actions, same play.
At least a fighter and a rogue and a ranger don't share much in common. A Battlemaster and a Rogue have virtually no shared mechanics. They play out very differently. The core casters? Between shared spell lists and common mechanics, everything might as well just be a wizard.
I mean, good grief, in our last session this morning, the warlock, the druid and the wizard all dropped fireballs at the same freaking time. Ok, the druid did it through a Staff of Fire. Fair enough. But, sheesh.