mempool.space caters perfectly to people that just "arrived" at this world and are looking for ways to better understand their knowledge about mempool, transactions fees, current block mining, etc.
That's a good point but I'd argue that the newcomers should first choose a decent wallet and stick to that for fee estimation instead of using any third party webtool. Usually when we seek such tools we want more advanced options such as the visualization of the mempool's history that Johoe's site provides or the current state that mempool.space shows.