The name is a pretty stupid comeback to use in a debate, and it's pretty toxicly used in the Spider-Man community. But I get where the name came from, and the idea behind it is valid. It comes from people thinking that Spider-Man is meant to be a solo character, and are critical of the fact that he feels like he's in the shadow of larger MCU heroes, most especially Tony Stark. FFH was about him stepping out of Tony's shadow according to a lot of people, but I think we can agree that the execution of that theme was a bit muddled and didn't come across as strongly, since him ditching association with Tony Stark was already a lesson he learned in Homecoming. And saying that he ditched Tony Stark in FFH is missing the point. The point comic fans are making is that he should have never been in Tony's shadow in the first place. Plus, his villains so far have all been Tony Stark victims that he was forced to fight, he still uses a suit made from Tony's technology, he still sees Tony as a very fond father figure, and the problem people have with that is the fact that traditional Spider-Man just doesn't roll that way. Avid, long time fans of the comics and the character are more likely to have a problem with this than someone who's being introduced to the character through these new movies.
Now disclaimer, I'm not saying you're wrong for not reading the comics. The complaints these comic readers are making are subjective and just because an adaptation isn't comic accurate, it doesn't make the adaptation of bad quality. The name "Iron Boy Jr" is stupid and doesn't take a debate anywhere. This subjective complaint from comic fans should not be used as an objective flaw of the character. But at the same time, comic/raimi fans aren't wrong for not liking MCU Spider-Man either. It's just preference, because the character of Spidey means different things to everyone.
There's a lot of bigotry on both sides. An example of bigotry towards comic fans would be someone saying "It doesn't NEED to be accurate to the comics. It's much more interesting to see a new fresh take!". This statement is highly insensitive to comic fans because it's made by people who aren't comic fans and can't relate to the experience of loving a comic book. I think statements like that are the equivalent of a Raimi/Comic fanboy saying "Iron Boy Jr", since they're both insensitive to the other party.
In short, the idea behind the name "Iron Boy Jr" comes from a subjective complaint from the comic crowd. It uses a subjective complaint and twists it to seem like an objective flaw when it isn't. There is also a big amount of bigotry from the MCU crowd towards these comic fans as well. At the end of the day, no matter how much people try to make their preferences and opinions fact, it's all just an opinion. Both sides should just respect each other's opinions and accept that some things about the character won't work for other people and refrain from stupid bigotry and insults. Like that's ever going to happen though. Fandoms are so annoying.
