Uniswap fees are insane right now (less insane than a week ago but still insane). So if any new wallet give rebate on fees paid or make transactions completely free, you will automatically acquire users.
Dharma, Argent and GDAX all paid their users withdrawals fees. But all of them stopped after DeFi exploded so much that they were paying from $12 to $20 per transaction (!!). This simply isn't sustainable for them and pretty much everyone else.
If someone keeps doing that, or starts as of now, they will simply be milked by the users who don't want to pay the fees. And when they stop (they will have to if ETH keeps up like this), everyone will leave for their previous wallets.
Trust me, that's a bad idea unless you have a magical business model that will pay it back for those expenses.