I've said this before, but this is a symptom of the very type of game that Smash Bros is.
When you played Street Fighter in an arcade in the 90s, you were putting money up to play against complete strangers. You were actually putting something on the line when doing this. If you lost, you were not only out a quarter, but you also had to walk back to the end of the line and wait for your turn again. Your opponents weren't going to be eager to help you learn and cut you any slack, either; they weren't your friends and they were putting something on the line themselves. The game in question was also explicitly designed around head-to-head competition in the first place. This kind of environment naturally bred certain attitudes. You wanted to find the cheap stuff and use it. You wanted to do everything in your power to win because there was something actually on the line to win or lose. With rare exceptions for extreme cases, soft-bans on characters or tactics didn't tend to stick because people who put up the money to play were unwilling to cede any tools at their disposal. The players couldn't tweak any gameplay options, and even if they could, the operator menu didn't have much to offer besides round count and cost per credit. You learned how to use--and how to beat--the cheap stuff simply because you had to. Developers had to put at least some effort into making sure that the games weren't too broken to severely hurt competition and income; those that were wouldn't last. And even after the scenes for these types of games transitioned from arcade to console, the players' attitudes and the developers' design philosophies largely remained the same.
Smash Bros started out as a console game that can be played competitively but has several significant non-competitive trappings. The typical player's first exposure to the game is not in a public setting like an arcade against complete strangers, but a more intimate, private setting between friends at home. It doesn't have an iron-clad default config designed around serious 1v1 play and is a heavily configurable game at its heart. In fact, in order to achieve ideal settings for competitive play, you kind of have to alter the game from its default configuration in at least some capacity. And the unfortunate side effect of being able to pick and choose the rules means that you're going to get at least some percentage of players more interested in lobbying for rules to suit their own biases and tastes than in learning things that they just don't want to learn.
It's actually kind of interesting to read up on the FGC's perspective of Smash Bros in Melee's early days. SSBM wasn't added to the EVO line-up until 2007, but there were fairly serious discussions about adding it to the line-up dating back to at least 2004, and the debates from around that time are illustrative of the differences between the two communities. One of the Cannon brothers (head EVO TOs), for example, said that the most appealing things about the game were (1) unique, elaborate stages, (2) items, and (3) more than two players at once, undoubtedly because those are the core elements of the game that clearly separate Smash from traditional fighters. It's not that surprising that EVO pushed for item play during Brawl's run on their stage when you consider their "default config is sacred" arcade era attitude and their desire to appreciate those elements of Smash that most-clearly separate it from the other games that they're used to playing.
Now, I'm not one to advocate for item play by any means, but I can at least in principle appreciate their attitude of "put everything on the table... unless there's a good reason not to" and the high threshold they set for additional rules and bans on that front. That attitude is why we're getting customs at EVO. I'm grateful for that much, even if they get the cold shoulder from the community from that point forward for questionable reasons.