Comment by AndrewStephens

Even that is very slightly biased, since you don't specify what happens when 2 cards accidentally end up with the same index. It's better to do the shuffle described in the document.

It is not just the predictability of the generator that is the issue (all PRNG are predictable really), what really matters is the size of the seed state, which should vastly exceed the number of value shuffles (52! - a huge number).