Yes for people that already are heavily invested into an 18v set up that might be worth it. Most people aren't in that situation though. And I'm not BIASED against Dewalt, I had alot of their 20v stuff too at my last job. 1 truck filled with Dewalt, one truck with Milwaukee. I've used both side by side, and formulate my opinion from that. I don't comment too much about Ridgid and Ryobi cause I don't personally own those, but they are both manufactured by TTI and are designed with the intent of Milwaukee always being the top dog.
As far as Milwaukee vs Dewalt in the BRUSHED 12v platform they are pretty even in the few tools they share, and I own both brands in those 4 or so core tools. Dewalt loses by default for basically ignoring that platform and not offering any brushless upgrades, or offering anywhere near the amount of 12v tools Milwaukee offers. Dewalts only perk is they have better lighting on some of those tools, and the handles are more comfortable IMO. other than that, there is no contest in the 12v department if you want to run those as your go-to platform and want real tool options.
And for the record, I have put dewalts compact 20v brushless impact driver side by side against Milwaukee's compact m18 brushed version, and used them to drive small lags into poles. The brushed Milwaukee is noticably stronger. I also have the brushless high torque impacts in the 7/16 hex drive versions for both brands.. the power is even despite Dewalt rating it stronger, the bits ALWAYS get stuck in the Dewalt and need to be banged out, and the Milwaukee just feels like a more solid tool when you use it. So if actually buying, owning, and using the same tools side by side from both brands and then forming an opinion is considered biased, then yes, that's me...
Between the last company I was working for, the one I work for now (who hired me and outright said "we want you to pick out all our equipment and teach our guys to do things your way), and the giant pile of stuff I have at home cause I sometimes buy stuff just cause I'm bored - I can comfortably say I've bought and tried ALOT of different cordless tools.