It's nuanced.

Once Mt. Gox confirmed, back on March 11, 2013, that they were not exposed to the chain from miners running v0.8, then at that point Eleuthria of BTCGuild (pool) switched their pool from running v0.8 to using pre-v0.8, which resulted in a chain reorg that cost BTCGuild six blocks they had mined.

If Mt. Gox had been using v0.8, that very well could have persuaded BTCGuild to stay on v0.8 and the pre-v0.8 would likely have eventually stopped.

Fortunately the ecosystem is now way more decentralized than in 2013 when Mt. Gox had a majority of exchange activity (i.e., dominant economic node) and BTCGuild (pool) had a near majority of hashrate. But exchanges run economic nodes, and as long as users keep their bitcoin on centralized exchanges, those exchanges can have influence on decisions.