[...] instead of your phone since a cell phone can easily be lost or stolen since you carry it around while your PC is less in danger.
That's why a backup is a must to recover your funds in case of phone lost.
I opened up the playstore on my Android phone and went on to install the Mycelium Bitcoin wallet app. It was then that I read the reviews and noticed that many users are complaining that their balance showed 0 all of a sudden.
Most of the reviews there who had problems are expecting that mycelium has support staff to answer and resolve their problems while using mycelium has the users full responsibility of using it, from any kind of lost funds and most of them are user's fault. Though there are sometimes that there's a software/server error which causes of not syncing the transactions and differs of balance in the app but that doesn't mean that your funds are lost, is just a software's bug your, funds can still be recovered using the seed and private keys.
I'm using mycelium eversince I started in crypto, (since 2015) and I always recommend this wallet to anyone.