If GitHub were to close tomorrow, you'd lose out on the social part temporarily, but there are effectively dozens of providers and solutions that could replace it.
The same could not be said for Figma, where if lost, you'd end up looking at the company that tried to buy it. That's what those laws are for.
No, Adobe/Figma was stopped because it would severely reduce competition in a market where there are already very few relevant players. That's all they can block.
Regulators can (and do) stop purchases which can be considered harmful to consumers. Just look at the Adobe/Figma deal.