Tempers can and do flare: I think this stems from the fatigue that accompanies being actively interested in an issue like this where we might encounter something on a weekly or even daily basis where we have to make decisions: as I've described elsewhere, it is a constant headache to choose between the principles of "pick your battles" and "silence is assent." This is why you'll see people making a mountain out of what might seem like a mole hill (in terms of a behavioral explanation). I wrote a post about fatigue not too long ago (in Feminist Only, I think people can still read even if not comment): Feminist Fatigue
I don't think losing temper or being bitter is helpful at all, but it's a tough situation because I understand on a human level why and how it happens.
I can see how it happens in any discussion about any topic. But some of it seems unique to the internet. I can have the same conversations in real life without any fireworks. It's different when interacting with someone face to face, whereas on the internet, it's more like posturing for an audience.
As for the "manosphere," there are veritable trashheaps of misogyny and toxicity out there for sure; but masculism isn't by fiat anti-feminist and I think it would be helpful for everyone to remember that there are valid men's rights issues, social issues, and so on that are unfair to men. I'd call myself a masculist because I care about men and their rights and how society impacts them too. It's just a shame that a lot of the movements that would work towards these ends have been co-opted by misogyny, anti-feminism, and toxicity. (Still, we should care, according to me!)
I've noticed that much of the criticism of feminism from the "manosphere" tends to point at things and events which they see as evidence that feminists believe in gender equality only when it is convenient for women. They decry what they see as a double standard, which leads some men to wonder, "Well do women really want true equality or don't they?"
I've heard some women lament that "chivalry is dead," suggesting that men aren't fulfilling some sort of gender role that they're still expected to fulfill. (Chivalry was never all that it was cracked up to be, though, considering what it actually entailed, historically.)
However, I've seen much more toxic areas of the "manosphere," which caught my attention after a few significant shootings where I learned what the word "incel" meant. This gave me the impression that there's a lot of young men out there with no real direction in life, few prospects, few ambitions, no real role models they can identify with, and believe that they're ostracized, unwanted, and will always be alone.
These are the ones who seem vulnerable to right-wing recruitment. While every generation goes through its wayward youth phase, this somehow seems different and more toxic. I'm not sure where it's headed.
I think you're right that feminism comes through different ideological lenses. My approach is one of social justice (feminism is a humanism), but I can certainly say that this isn't the only flavor. So when you ask about MTG, I'm not sure what to say: if her worldview could be perceived as a feminism by somebody for some reason, it's so alien from my values that I'd have to break it down into specific aspects to agree whether it's something I could call feminism or not.
MTG might be considered a beneficiary of feminism, even if she's not a feminist herself.
I think I can generally see eye-to-eye with most socialist-oriented feminists who believe in economic justice.