Absolutely! I wrote MRP systems for a pharma manufacturing in Florida and the kind of stuff I had to do on a daily basis far surpassed the complexity of your breathtakingly-beautiful but typical project-management webapp or customized T-shirt webstore. Let me be clear, complexity has absolutely nothing to do with the merit of one product vs. another. KhanAcademy code could be simple as 2nd grade math but nothing I ever write will ever be as beneficial to the world. However, complexity is expensive, takes time and dedication, and rarely pays off in the short-term.
There is a reason most supply chain software installations run in the millions to tens of millions. Here's an example of something I wrote while ago: A drag & drop scheduler in JS, kinda like Google Calendar that lets you schedule production jobs on different equipment, across different labor teams. When you change a single job on the schedule, it auto-calculates the entire requirement for the entire company. Moving one production job up (say shampoo for customer A) could end up in the company losing $500k because one of the ingredients that went into shampoo for A also goes into conditioner for customer B. This particular item has a lead time of 3m from China. And since order for B is significantly larger in amount, every single day of delay is money actually lost because you bought all the other raw materials for B on credit from the bank and now have to pay interest on it, while it just sits in the warehouse waiting for the raw material to be flown in from China.
Of course, this is something you want to avoid in the planning stage itself. And that's what the software does and warns the user within seconds of making any changes. One tiny bug in the code, say it doesn't correctly factor in the internal lead time from QC (this particular chemical needs to be sampled for microbiological contamination) and you just delay the project by a week. Putting up a pretty website is hard work but it is nothing compared to hiring 20 people to spend 3 months mapping out the multi-stage routings for 500 different SKUs. No tech-VC wants to invest in businesses that require a tremendous amount of operational labor. That's what banks are for.