This has been my biggest struggle with rewrites where I’m currently working. We have several large, messy old codebases that everyone agrees “needs a rewrite” to (1) correct for all the early assumptions in business needs that turned out wrong, (2) deal with old PHP code that is very prone to breakage with every major new PHP version released, and (3) add much needed architectural patterns specific to our needs.
I’ve seen rewrites of portions of the project work when they involve myself and one other mid-level dev who has a grasp on solid sw engineering practices, but when the rest of the (more senior) team get involved on the bigger “full rewrite”, they end up quickly making all the same mistakes that led to the previous project being the mess that it is.
Sure, it will be using fancy new PHP 8 features, and our Laravel framework will force some level of dependency injection, but the you start seeing giant God classes being injected over here, but duplicated code copy-pasted over there, all done by “senior” devs you feel you can’t question too strongly.
To that end, an open and collaborative culture in which you start the rewrite with some agreed upon principles, group code reviews and egos kept in check, are all necessary for this to work.