not enough gluten development.

knead it while gradually adding flour until it doesn't stick anymore

How are you making it? Looks to me like it didn't get kneaded enough before proofing.

Too much water. Get a digital scale so you can precisely measure flour and water and get the right consistency. Do you have a metal scraper? That's also necessary.

Get a non-stick pizza pan and forget about stones.

>>7397171
>>7397169
I thought it was because I wasn't kneading it enough, so last time I tried kneading it for about 5 minutes longer than usual. It didn't help. I have a hand mixer with dough hooks, should I be using that?

Keep kneading in more flour until the dough is no longer sticky. In my experience doughs have a "base" amount of flour and then an amount to add in if necessary.

>>7397169
This. If it tears apart, the gluten isn't developed enough so you knead more. If it's too sticky, there isn't enough flour so you add more flour.

You can't always just blindly follow a recipe with bread dough. There are variables like the moisture content of the flour and the humidity level in your kitchen/house that affect the dough so you need to follow the basic guideline of the recipe, then may need to add more flour or more water/liquid to get the dough where it needs to be.

>>7397177
You could also try using bread flour instead of AP flour since it has more gluten in it.

>>7397185
I did notice recipes calling for bread flour but I ignored it. I'll try bread flour next time.

>>7397186
I always use bread flour for pizza dough, it develops a lot more gluten and stretches much better than dough made with AP flour in my experience.

>>7397188
AP flour can work, but it requires more kneading then you'd think (especially since you're reading bead flour recipe).