system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Why are wizards/witches limited to wands?

It's well known that wands consist of a wood rod and a magical core, but why do wizards stick with a footlong stick that channels their powers when they could use a staff which would allow for a much larger or multiple items as it's core to better channel or even amplify their power? Say something like a willow sapling with a dragonbone core.
gpt
They aren't. According to Ollivander, a wizard or witch can channel his or her power through any instrument encasing a sufficiently magical substance. However, after his research, he came to the conclusion that the combination of wand wood properties, shape, flexibility and wand core (Ollivander is very adamant that only phoenix feathers, dragon heartstrings and unicorn hairs are appropriate cores) gives the best magic over everything else.

So sure, if you want, you can use a staff or orb or iPod to use magic, but the spells won't be as effective as if you had used a wand.