You're essentially proving my point; why even have these people when they're, by your admission, walking talking aisle signs?
There's certainly validity to your argument, and my point is that employees do need surface-level knowledge about general product categories in their store, which we both agree upon. In my previous posts, part of my gripe with Home Depot is their employees often fail to be helpful in finding basic items that aren't of specific brands. For instance, those stick-on felt nubs used on cabinets can be in any upwards of 3 aisles dedicated to cabinets, drawers, shelves, etc. It would save me time for an employee to remember where the shelf space is for those type of products.
I'd be happy if they could do this even 50% of the time. I'm not expecting perfection. At any given Home Depot I've been to, I've only gotten actual help about 5% of the time. Contrast that with almost any other hardware store, including ones of equivalent size, and it's a different story. Even the employees of Lowes are of better assistance. Orchard Supply Hardware is even better, although their stores are smaller. This doesn't even stop at grocery stores; employees at Target, Walmart, and various grocery stores are more helpful in my experience and know about their inventory to a greater extent than those at Home Depot.
I don't know exactly how other stores like Lowes manages to improve this customer-employee interaction, but if I were running Home Depot in optimal conditions, I would create incentives for employees to familiarize themselves with products and various product categories. If they could make it to optional trainings, watch short videos, be of help to pretend customers, pass quizzes, all of which are voluntary and are not included on an employee's performance record, they could see raises and other benefits. But I've never been an employer, so I don't know how well that would work in practice. I also have no idea if Home Depot doesn't already do these things to any meaningful degree.
It may seem like I'm ranting and raving about Home Depot, but that's only because I don't think my expectation that employees should be paid to do something kinda hard isn't an unreasonable one. Unless they're stocking shelves or helping me cut wood, I can't see their presence to be of value. Better signage and promotion of their mobile app(which I only learned of today) could easily replace these employees, and probably will once the next economic downturn hits.