Don't base it off your competitors. Do some user testing that will validate your answer in either direction. Bill your client for the user testing.

E-Commerce Sites Need 2 Types of Breadcrumbs (68% Get it Wrong)

While breadcrumbs may seem like a pretty uninteresting site element, during our recent Homepage & Category Usability study they proved themselves to be vital navigation paths. Perhaps more interesting is that the study revealed that e-commerce sites should offer 2 types of breadcrumbs: both hierarchy-based and history-based breadcrumbs.

Yet, when benchmarking 50 major e-commerce sites we found that a staggering 68% suffer from sub-par breadcrumb implementations: 45% have only one type of breadcrumb (typically hierarchy-based, lacking the history-based), and 23% don’t have breadcrumbs at all.

https://baymard.com/blog/ecommerce-breadcrumbs

But 2019 hasn't even started..

I think it depends a lot on the products the store offers. If it's particularly 'wide' (many categories) or 'deep' (many layers of subcategories) then breadcrumbs are a great way for a user to keep track of where they are in relation to the rest of the website, and I would consider them critical for a positive user experience. Yes, people are more educated nowadays, but they're not educated about your website. Every shop is slightly different, and breadcrumbs act as a map to new visitors. Just because I know how to drive, doesn't mean I know my way around a city I've never visited before.

Like Ryan said, it's absolutely worth testing, but if you/your client doesn't want to spend time/money on testing this particular thing, I'd keep them in as long as they will change from product to product. Meaning if every product in the store is in one category called "shoes" then breadcrumbs aren't providing any value being there, because they say the same thing on every page. Home > Shoes > [Product name]

Yeah, they're not 'cool' but they're pretty helpful. We were experimenting with 'tabcrumbs' at work too. They work in a similar way but the child breadcrumb doesnt disappear and they look like tabs.

Breadcrumbs can be really useful if your users are digging down through your deep architecture one layer at a time and have some use for jumping back up the hierarchy 2 or more layers.

They're not especially useful if your architecture is shallow. Also not useful if a typical flow has you jumping between categories or skipping deep into your architecture from hubs. Most ecommerce sites do these things. In this case, breadcrumbs are irrelevant to the user's flow and introduce potentially distracting information.

I would recommend keeping your architecture as simple as possible, account for jumping between categories/hierarchy, naming your pages extremely clearly, and distinguishing elements of your hierarchy clearly. For example, pages with many products should look different from a page with one product.

Don't A/B test this.

Of course if your application has a deep hierachcal structure. You can achieve another result by doing it with filter and sorting but therefore you will need a logic behind that so. Breadcrumps are sometimes a good choice and cleverly build quite useful.

Take into account breadcrumbs are not only informative, they're also navigation. They allow a user to quickly switch to parent categories/subcategories bypassing main navigation.

Do they have breadcrumbs on their existing site if they have one? If so, you could just check analytics for click rate on them.

Yes.