That used to be the prevailing opinion. Pre-mined coins were generally regarded as scams or pump-and-dumps. But after Ethereum which is almost all pre-mined sharply rose in value, there seems to have been a change in public perception. This is what opened the gates for the new generation of altcoins, also known as ICOs. They don't pretend that they're anything else than pre-mined. In fact, the huge sums that the pre-mined coins are sold for is used for marketing as a measure of interest in their coin. It's a strange new world.