Gavra,
No Gadol anywhere said that contributions to “Adopt A Kollel” are mandatory, just as contributions to any kollelim over the past 70 years haven’t been mandatory. It’s a voluntary Yissachar-Zevulun partnership which is by definition hachzakas haTorah and not tzedaka.
Harav Heinemann’s views are most certainly mainstream and can’t be written-off merely based on his one position regarding ovens.
You seem to enjoy quoting things in the name of “Gedolim” a great deal, even though you can’t ever seem to back them up. After “work”, why not try learning a bit instead. You may want to start with Hilchos Tzedaka.