If anything this article shows that concurrency is a big issue. It is such a big issue you have to write in-memory single threaded processor with custom journaling. If you have established workflows with MySQL and a team knowing how to work with it, throwing all that to do LMAX is not cost efficient. While there are domains where such approach is suitable and even required due to strict transaction ordering, Shopify case doesn’t look like one of them.
https://martinfowler.com/articles/lmax.html