Technically, the Amper plugin is developed in the IntelliJ monorepo and published together with IntelliJ IDEA, so it's available in all versions of IDEA that have been released since we started Amper.
For instance the IDEA 2024.3 and 2025.1 releases have a corresponding Amper plugin.
The only reason we're telling users to use the IJ EAP version is because the Amper plugin moves fast and most of the recent features are only available in the latest EAP versions. Also, the plugin is currently coupled to a single version of Amper itself, so if you're using Amper 0.7.0 you need a plugin that knows how to deal with this version. In the future we'll work on compatibility with multiple versions, but at the moment it's simpler to move forward this way.