BTC and other proof-of-work cryptocoins require active upkeep from the CPU/GPU/ASIC miners maintaining the network.

Hardware, and electricity investment is not static for miner upkeep. A fun feature of most cryptocoins is the ever increasing demand for hashing power, forcing miners to constantly consider the value of their real costs versus the real value of the protocol they apply their equipment to.

So by design, the network effect of cryptocoin miners will flock to whatever the current best design is on any given day.