Removal of composer plugin (infection plugin installer) in a new major?

[Ocramius]

Related: slevomat/coding-standard#1413

The idea is quite simple: composer plugins are an overall pain. As a long-term maintainer of ocramius/package-versions, I managed to finally chop its head off with composer-runtime-api: I was lucky that the "plugin" part in my plugin was no longer necessary.

Since composer/composer:2.3.8, composer plugins require additional config flags to run a clean installation. The effect: hundreds of repositories with failed builds overnight (literally: I receive 5~6 notifications for broken builds every day), without any change in their pre-existing state, which is extremely annoying for stability.

Unless there is a vital reason for shipping with a plugin installer, can it be disabled by default, and introduced manually in a new major release?

In practice, this means removing one dependency, making it opt-in, but removing such a dependency is a BC break, and requires a new major release.