I’d call it “Modular”.
If it works… no problem.
I cross breed tools all the time.
Whatever works, they are probably made at the same place now anyway.
I have three black and decker battery tools, a drill, pole saw, and weed whacker. Each one I bought because I already had decker batteries. So the drill went out this afternoon and just wanted another cheap decker drill. I went to four places before I actually found one. So now I have six batteries and three chargers for these cheap junk tools… I’ve also got porter cable but only a couple batteries. At some point I guess I will be faced with throwing everything away and starting over.
I’d say it’s agnostic!
Yes, it is. You must atone. For a donation of $100 the Church of Brand Loyalty will say a short, secret prayer of forgiveness.
Whatever works to get the job done.
The nice thing about standards. Everybody’s stuff works together.
More like one company that bought up many brands. It’s just paint color now. I do use a dewalt blade on my Milwaukee chop saw though.
If you need an adapter or special accessory that the brand you are overly loyal to and they don’t have it, what are you going to do?
A neighbor gave me his rechargeable Ryobi driver-drill, worked great until batteries went dead. You might think most any recharger cable of recharging driver-drill batteries would do the trick, but you’d be thinking incorrectly … lol … only a Ryobi brand recharger may be used to recharge Ryobi rechargeable driver-drills, at least from what I can discover. ??? I must atone… I must atone … lol …
When I bought my cheap junk b and d drill last night, right next to it was a transformer drill that had a sander attachment. I paid a little more and got that instead. Actually seems kinda useful. Snap off the drill attachment and snap on the detail sander. I’ve got six batterie now anyway.
You can buy a Ryobi charger for $35 at Home Depot. I have a few Ryobi batteries and save by buying additional tools without the battery.
I ordered on from Amazon, $25.
I have several old Craftsman 19.2V rechargeable tools. Sears doesn’t make those batteries anymore, they sell repros. I bought an adaptor and now I use a deWalt battery. Better tech in the battery.
Once you’ve attached Milwaukee into Pittsburgh you can never change back to Milwaukee-Milwaukee.
That would risk disturbing the beer liquor continuum and destroy every foosball table on Earth.
Or get it “free” when you buy another one of their tools. 
Sometimes I buy stuff I had no idea I needed until I see it. 
Who doesn’t need a battery operated whatchamacallit? Actually, the bundles sometimes are a great deal- sometimes cheaper than the tool alone. Although those are rare instances. Usually still much better than separately.
I think it was my porter cable drill that I bought way back. It said bare tool but I didn’t know what that meant. So back to the store to get the two battery and charger set. I wondered why the thing was so cheap. So then I bought the bare power saw. Guess you need the super duper battery because it wouldn’t even cut quarter inch plywood. Still haven’t bought the larger battery so just collects dust.
I noticed that the tools with battery and charger were a lot more expensive than the tool alone.
Oh gee I forgot. I’ve got de Walt too for my nut driver. So that is at least three brands of batteries.