It's not all but some projects. I must remind you that if scalability was not only the consideration before try to launch your project on a protocol. The scalability that owned by polygon doesn't have big gap with BSC but people must also think about how much the demand that gained by the platform like BSC. This will be helping a new platform to grow even more. Remember that if a protocol has more users and then it may give more hype compared with a protocol that has less users compared with another one. BSC has better popularity among the crypto users. that makes the new project are still interesting to launch their platform on the BSC.
They were thinking polygon as an alternative to the BSC and ethereum but i must be honest about this if polygon didn't have a lot of demand like BSC. this can be seen from the TVL on plygon and BSC defi platforms.
BSC has more TVL compared with polygon defi. that means if BSC has more popularity that can give hype for a new project compared with polygon. Both were second layer solution for ethereum.