It’s like how the US can block mergers between companies that aren’t based in the US. Companies want to operate in these markets. If a major regulator says no, they have two options. Remove themselves from the market the regulator that denies them regulates or spin off into multiple companies if that’s actually possible operationally for the multiple companies to exist. Somalia regulators can block an acquisition in their country but that wouldn’t change much for the company as Somalia has a small market and little international influencer. If China or the US or the EU say no, a company that wants to operate internationally will lose a huge market and will now have a way more difficult time doing business from other companies that operate multinationally