This drives me crazy. Local stock search is different on each store and most don't work correctly.

Try searching on Walmart to find local stock. You have to click "In-Store", then change the Fulfillment Speed to today and tomorrow to find things that are in stock. Except now they also show results from other stores, like Advance Auto Parts, and there's no way to filter that garbage out.

I tried searching Academy Sports for local stock. The list of items says it's in stock but when you go to the individual item it says it's OOS.

Lowe's and Home Depot local stock does seem to work reasonably well, for now.

analytics have confirmed that surfacing inventory status is bad for the customer because it reduces conversion

Bad for the store you mean? Because the customer doesn’t convert (buy) something if it says “hurry only 1 left in stock” because everyone knows that store inventory is inaccurate and they ultimately don’t have 1 in stock, they have 0 in stock?

The way I interpret the comment, it says this:

A. [explicit claim; humorous] Analytics confirm that, if you show people whether products are in stock locally, they won't buy those products on your website.

B. [by implication] This is bad, because it "lowers" your sales. So you can't display this information.

C. [by implication] The retailers are making a mistake - the reason people don't buy products on the website when availability information is displayed is that they go to the store and buy the product there.

D. [summing up] If you measure something you don't care about, you will end up doing things that make you look like an idiot.

close enough

That's not a good explanation. Either GGP was being sarcastic or is corpo-brained. GP was confused because, unfortunately, both are equally likely these days.

Interesting. Do you have sources to read more about it?

Is it good for conversion when I give up out of frustration at your broken store and decide to just get the thing on Amazon instead?

This isn't just hypothetical: for a while I was using QFC (Kroger) for grocery pickup, but after one too many instances of adding an item to my cart and then only finding out at checkout that a third of my items weren't actually available, I said to hell with it and switched to doing all that at Whole Foods instead, since their inventory counts are actually correct.

I did just check this, and I found it fairly easy to filter by in-stock at my chosen store. Did you set a preferred store then filter by the "store pickup" option? Doing that, I returned results for chair mats with the option to check other local stores.