I wish newer Marvel movies would let their protagonists be protagonists instead of sidelining them to develop other characters. Like Black Widow, Shang Chi to some extent and now Doctor Strange. Wanda was probably shoehorned into the latter film to "atone" the fact that she never had a solo film. And I bet Thor 4 is going to sideline Thor in favour of his supporting cast (i.e - Lady Thor).
I think WB was always trying to a reverse Marvel approach. In the late 2000s, before the writers strike, they were going to make Justice League: Mortal with George Miller. Then I believe that would've branched-off into other solo films (i.e - movies with Wonder Woman and Green Lantern). From what I hear of the script and what's been revealed, it seems far better than the Justice League we got.
Batman V Superman would've made over a billion if it was well received by audiences. The hype was there. It opened to over 400M worldwide and had an opening day of 80M in the North American box office. Those were numbers comparable to the first two Avengers movies. The problem was, Zack Snyder was one of the key figures in their cinematic universe. Even Suicide Squad had a massive 65M opening day and Aquaman made over a billion. Unlike Marvel before the MCU, DC arguably had more brand recognition, so I don't think it was necessary to give everyone a solo film before teaming everyone up.
I think they were attempting to go a solo film root, had Green Lantern (2011) been a success.