They do have but nobody takes them seriously. Plus if you want 1000000 different versions of bitcoin, go ahead, but dont cry when nobody invests in your altcoin.
what a silly fool. having a different implementation EG bitcoin ruby, bitcoinj, bitcoinxt bitcoinBU bitcoincore.. are not "altcoins".
stop trying to presume anything not coded by non blockstream employees must be an altcoin.
the truth is that all bitcoin implementations are actually handling bitcoin data..
dont confuse implementations by other groups with fork proposals.
core AKA blockstream should not have any decision making power to restrict the communities desires. and if you think that "core" has been the guys that have made bitcoin a $10bill industry then you are so wrong..
the current coders you deem as the "core" devs were not even around a few years ago. so please stop trying to make them out as the inventors or the masters of the crypto universe.
now
to add details to rizzlarolla point.. because i think "realbitcoin"(the NXT/sidechain fanboy) is missing the whole point that has been raised a few times
there are 6000 bitcoin nodes.. so if "realbitcoin" thinks the minority chain will retain 0.0001% users.. thats not even 1 node..
even if "realbitcoins" under 0.000x% is a funnier number that helps show forks are not dangerous (slapping himself in his own face about controversy risks, using his own words) lets atleast stick with facts,
and so truth is.....
initially if a fork happens it will happen at 90%.. meaning 5400 have already converted to the new code for the fork to be acceptable to go live..
leaving 600 nodes on the old (now minority chain)
the reason for this is that miners will flag their blocks and when it hits 75%, that is the warning bell to get people to realise its time to move over.. then miners will wait until there are an acceptable amount of nodes to ensure their blocks wont get orphaned to actually start making those new blocks, knowing they will be accepted and their rewards are spendable..
so presuming there are now 600 nodes on a minority chain due to a fork happening, that minority chain will only getting 1 block every 2 and a half hours* and soon they would get peed off with having to rebroadcast their transactions, to try keeping them in the mempools. for these reasons:
1. the 5400 wont retransmit the transaction because technically its already confirmed in the majority chain.
2. the minority chain will have to start IP banning 5400 nodes to try to find a successful route to a minority pool.
3. the mempool of the old nodes/pools are full of ALL transactions. 2500tx every 10 minutes = upto 40,000tx with only a gap of 2500 in a block
4. every time those 37,500 tx that we not added to the minority chain each 2.5 hours* have to go through the headache of rebroadcasting again with a higher fee..
this would cause merchants WITHIN HOURS would see the delays, the increasing tx fee costs and the headaches so they will switch..
leaving only a few laggers circle jerking themselves with coins that are costly to move, slow to move and unable to buy real world things with..
it would take MONTHS for the difficulty to adjust on the minority chain, but hours for users to see the problems and move away from it. in short killing off the minority chain.
this is why bitcoin is different.. bitcoin has real world uses and real decisions will be made in hours.. ethereum however is just a sandbox with no real world infrastructure, thus ethereums choices are not as apparent and people are just juggling the vapour of 2 coins that both do nothing so both have no positive choices of use to cause any fast decisions
*i say 2.5 hours(15 blocks) instead of 9 blocks, because 10% hashpower mathematics works differently in reality