They hope to incentivise customers to use intel foundries by splitting them off. Intel compete with AMD and nvidia in many segments, so neither of these companies would want to manufacture their products at intel. But turning their foundries into a separate company could maybe change that (probably not). Their foundries also bleed money like crazy, separating them could stabilize share prices for the ‘main’ intel brand.
They do not prevent you from adding repos and installing from those. They don’t even try to make it slightly more difficult to do so than it was before. Microsoft force you to use edge. Cannot really disable it. Can’t remove it. Can’t simply switch away from it. See the difference?