I think some more healthy competition against Core would be welcome
You are confusing "healthy" (ie positive-sum) competition among consensus-critical blockchains with unhealthy zero/negative-sum contention within a single consensus-critical blockchain.
Altcoins are Bitcoin's healthy competition. If Bitcoin isn't competitive we'll use Litecoin, Primecoin, and Monero instead.
Classic and other XT-like governance coup attempts are declarations of a war that only one side can win.
I think "healthy" competition can come from both inside and outside of the Bitcoin ecosystem. Internal competition becomes problematic when productive discussion and collaboration devolves into mudslinging, which it too often does.
You've got it all wrong. "Mudslinging" is good. Vigorous debate is the crucible from which truth emerges. And Bitcoin runs on drama!
Healthy (ie positive sum) internal competition comes from implementations competing to best preserve/protect/promulgate the critical consensus. Unhealthy (ie zero-at-best but-probably-negative sum) competition comes from contention-generating hard forks that risk catastrophic consensus failure.
Gmax mapped it out here:
competing implementations are healthy; but the ones that threaten to break protocol are dangerous.
Competing implementations of Bitcoin, such as Litecoin and Primecoin, are called altcoins because they establish their own independent alternative socioeconomic consensuses/majorities.
Hostile implementations of Bitcoin, such as XT and Classic, are declarations of war because they attempt to threaten Bitcoin's existing consensus-critical distributed ledger.
But there are other implementations, like libbitcoin I believe, that aren't altcoins, and are net positives for the
Bitcoin ecosystem. Isn't that right?
It gets confusing and idiomatic (esp for non-native speakers) if we have to distinguish between the friendly positive-sum competition of btcd vs the cutthroat zero-sum competition of GavinCoin.
I'd classify other implementations like libbitcoin and bctd as
complementary, not competing, in that they all share the same goal of maintaining the One True Holy Ledger.
But let's defer to the core dev, if gmax has a better suggestion for the taxonomy/nomenclature.
Open source software generally both cooperates
and competes. Handled well the benefits of the former offset the costs of the latter and the result is a gain for everyone. --- but software differentiating in consensus rules is the worst kind of competition: competition here can deprive users of the practical freedom to use their preferred software, and the fight risks leaving a salted earth in its wake.
This is not completely unheard of outside of consensus systems: A less powerful version of it exists in the form of file format compatibility. Microsoft was a pioneer of business strategy based on making incompatible extensions to formats, first leveraging their network effect and then-- after introducing incompatible changes-- using it against them, an approach they themselves called
embrace, extend, extinguish. Worse than zero sum, these kinds of moves can be tremendously damaging overall.
Bitcoin's creator described alternative implementations as a likely "menace to the network"-- words which I think were spoken with an early insight into the incredible difficulty in making distinct software actually consensus compatible even when that is your highest goal, an art our industry is still just learning. I wish we'd built mechanisms earlier on for better ways to enable diversity in the non-consensus parts without ending up with unintended diversity in the consensus parts. But we play the hand we're dealt.
The potential harms from consensus disagreements from mistakes in re-implementation are tiny in comparison to those from adversarial implementations which intentionally push incompatible rules.