In page 2 of the titlesec documentation, Javier Bezos writes
titlesecworks with the standard classes and with many others, including the AMS ones, and it runs smoothly withhyperref. Unfortunately, it is not compatible withmemoir, which provides its own tools with a limited subset of the features available intitlesec.
I don't use the memoir document class so I am not familiar with its features, but I've made a few simple tests (really few and simple) using it together with titlesec and couldn't detect any problems. To what extent can titlesec be safely used with memoir? Which exactly are the incompatibilities mentioned?
memoirmanual. As I understand it, they're not really incompatible, but you can't really mix and match their respective ways of redefining the sectioning commands. – Alan Munn Oct 29 '11 at 01:22\usepackage{titlesec}\titleformat{\chapter}[display] {\normalfont\huge\itshape}{\chaptertitlename\ \thechapter}{20pt}{\Huge}will still allow using the two optional arguments of\chapter. – Gonzalo Medina Nov 04 '11 at 16:20titleseccommands for specifying titles, you should have no problems withmemoir. But you cannot mix and match. – Seamus Nov 04 '11 at 17:51titlesec. I have discovered no case in which it is not easier to do withouttitlesecwhat I was trying to do with it - usually much easier. Even where I initially wrote code withtitlesec, I've eventually had to eliminate it when debugging. Plus, you can get Memoir sections to play nicely with microtypography (like the standard classes), but nottitlesec. I have no fix fortitlesecsectioning, but my fix works fine with Memoir. – cfr Jul 10 '18 at 23:43