The difference is the loom is performing linear work.
Programming is famously non-linear. Small teams making billion dollar companies due to tech choices that avoid needing to scale up people.
Yes you need marketing, strategy, investment, sales etc. But on the engineering side, good choices mean big savings and scalability with few people.
The loom doesn't have these choises. There is no make a billion tshirts a day for a well configured loom.
Now AI might end up either side of this. It may be too sloppy to compete with very smart engineers, or it may become so good that like chess no one can beat it. At that point let it do everything and run the company.
Anything that can be automated can be automated poorly indeed. But while it has been proven that textile manufacturing can be automated well (or at least better than a hand weaver ever could), the jury is still out if programming can be sufficiently automated at all. Even if programming can be completely automated, it's also unclear if the current LLM strategy will be enough or whether we'll have another 30 year AI winter before something better comes along.
The difference is that one can make good cloth with a loom using less effort than before. With AI one has to choose between less effort, or good quality. You can't get both.
Anything that can be automated can be automated poorly, but we accept that trained operators can use looms effectively.