Unless, of course, you have one of the lower end phones (which is exactly the kind he is referring to) and it doesn't have enough internal storage for you to replace all the built-in apps (which can't be removed without root).
On the other hand, things have come along enough to give you quite a substantial amount of room even at the low-end. I paid $149 For a Huawei 881c (Net10/Tracfone), and I've got 2GB of internal storage to play with for apps (something like 512MB out of the box, but you can tweak it w/o root to take the whole 2GB and shove your media onto a micro-SD chip).
At this point, the lowest of the low-end phones are only for, well, suckers. You can save up a few pennies and get something cheap, and do it without having to sacrifice too much out of the gate. For example, on my phone, this is what I don't have: the magnetic compass is missing, I can't tether it (w/o rooting the thing), it's 3g instead of 4g, and performance is only like 95% of the top-end flagship phones (e.g. barely noticeable). However, that's about it, and it doesn't really impact what I do on it.