When you start crochet, nobody tells where every loop ends up in: Every loop basically counts as a single line segment, and you just draw a grid out of them. The thing about grids is there is the ‘fencepost error’.

What people should know from the start is that if you make a 10x10 grid, you generally start going from bottom left to right, pulling 10 loops horizontally, then 1 up, then 1 back to the left. People just say “chain 12” though, which is confusing to noobs. From there on out you stop doing chains, and do crochets, which means inserting the hook wherever you want to draw lines from and alternating between adding horizontal and vertical line segments. When you stretch a crocheted fabric, each crochet can move yarn from the horizontal loop to the vertical one or back, to stretch one way and shrink the other. But the foundation chain was made with subsequent horizontal bits and will not stretch! (and chainless foundation rows exist but are not even mentioned to noobs)

So beginners will be confused by the fencepost error which requires mixing in the occasional ‘chain’ at the end of rows of ‘crochets’. Since you pull new loops out of identical looking crochets 90% of the time, but then have to deal with different looking ones on the edge its easy to mistake a vertical bit for horizontal or vice versa and accidentally increase or decrease unintentionally.

So many ruined projects and people giving up on the hobby just cause everybody is making tutorials and nobody is explaining the logic.