Guys like Wladimir, Pieter, Gavin, Cory Fields, Gregory Maxwell and Luke Jr have a voice because they’ve contributed many thousands of lines of code. (Lines of code are only a proxy for impact).
You may have noticed Mike Hearn isn’t in the top 100 contributors list. He is the primary author of the Java implementation of a bitcoin library: https://github.com/bitcoinj/bitcoinj
He started it in 2011, definitely early. But a substantial amount of bitcoin core work had already set the path. There are also similar implementations in many different languages but they are not the primary reference implementation for full nodes.
According to Hearn’s blog post: “I’ve talked about Bitcoin on Sky TV and BBC News. I have been repeatedly cited by the Economist as a Bitcoin expert and prominent developer. I have explained Bitcoin to the SEC, to bankers and to ordinary people I met at cafes.”
Being cited by journalists is not the same as being a primary contributor.
The disagreement between Hearn and the other developers isn’t about whether to increase capacity, it’s about how. Many of the primary full-node contributors believe a hard-blockchain-fork is a risky approach. Lots of work is being done to explore better options, like segregated witness (http://gavinandresen.ninja/segregated-witness-is-cool).
Mike Hearn tried to (very aggressively) push the idea of increasing the block size with a hard fork. In fact the patch allows node operators to vote and 75% adoption is needed. When it looked like that wasn’t going to pan out, he created Bitcoin XT where “Decisions are made through agreement between Mike and Gavin, with Mike making the final call if a serious dispute were to arise.”
So the claim that Hearn not being able to take over decision making power for the bitcoin community is evidence that bitcoin has failed seems to show something slightly different. It shows that open source software methodology of forking and adoption lets the best implementation win and prevents hostile takeovers.
Mike Hearn is not as impactful to bitcoin development as he or recent news would indicate. Mike leaving the bitcoin community has little impact on the future success or failure of bitcoin.