I agree that the Ethereum blockchain is the most popular, but the commissions in the Ethereum blockchain are the highest, especially when tokens are moving.
Almost everyone has a wallet in Ethereum, so Ethereum is used for bounties and airdrops. The more popular the blockchain is, the higher the commissions in it.
Now there are many other blockchains that are faster than the Ethereum blockchain and the commission in them is lower, so there is a lot of competition among blockchains and many have wallets in different blockchains.