Structure definitely makes a difference: I've worked in tech companies with 2000 employees that were more nimble and higher functioning than many a 100 person startup. Even among very large companies, there's clear tradeoffs that lead to very different actual outcomes.

That said, the larger the company, the bigger the problem and the harder it is to change direction when your organization is messed up. And as a company grows, an organization that was optimal can become a disaster.

A 100k employee organization is always going to have some parts of itself that are going to feel glacially slow. But there are companies that big that still deliver great products, while others seem to only exist due to inertia, as they couldn't build anything new that people wanted at any speed. But as Microsoft has sown us, a few organization and leadership changes can turn a company that at some point looked undead into relevance. Companies like Google and Meta are large enough that, even if we made the leadership completely incompetent, the companies would probably be valuable enough to survive for decade, just on inertia