Having more than one option in a wallet is much better than just having to deal with btc alone if most newbies as well as even experienced people here are willing to earn anything instead of btc alone. You know this forum gives you chances to earn in Eth and some other alts too which is why having a preloaded set of keys of different coins in the same wallet is highly preferable if you ask me.
just because it is possible to receive payments in an altcoin doesn't mean people are going to store it and a wallet is usually preferred when you aim to store the coins. some don't even store bitcoin, they dump it for fiat right away. it is more true about altcoins in which case receiving them in their exchange account is a lot safer than using some of these multi coin wallet options.