Did they maybe say replace the brakes using complete backing plates? A complete backing plate assembly is all the working parts of the braking system at one wheel - shoes, magnet, springs, clips etc. It's like getting a complete new braking system - except for the drum. Usually, the cost of needed miscellaneous parts added up exceeds the cost of a complete backing plate, it's easier to put on, and you have a renewed system. And it does not cost much more than just shoes. So it probably makes sense. Plus, if you want to, you could get self adjusting brakes - which I really like. No more crawling under the trailer to adjust brakes (assuming everything is working correctly). The cost of a complete backing plate of self adjusting brakes is hardly greater than standard "you" adjust brakes.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch