1. “What do you mean by “opportunity”? “
Open a histroy book in the mid 19th century there was a surge of nationalism worldwide. Among Many jews this manifested as zionism. Then there was the Balfour declaration and San remo confrence
2. “Maybe I’m wrong, but I didn’t think that the Mizrachi movement was started by Gedolim “
You are. Granted there werent as many as those that opposed. I beleive all agree R” Yitzchak Yaakov Reines was a Gadol
3. Who decides who are “The biggest Gedolim” ?
4. ” Maybe the Chassidim thought that the Gedolim in past times would have become Chassidish.”
Lol, they do! All movements are new at some point, though their adherents claim to be following the past. This is my point (and ZD’s and DY agreed as well)
Much like your modern notion of “Daas Torah” is a new idea, though I’m willing to bet you claim it always existed.
Even among those who claim Daas Torah always existed, I dont think any of them ever claimed if a person votes for a different party than the one supported by Gedolim he is no longer ” Shomer Torah and Mitzvos.”
see here http://www.theyeshivaworld.com/coffeeroom/topic/is-haredism-a-movement/page/4#post-640251