Translators are not developers. They may even have no technical skill at all. The only tool they need from the rich Qt environment is Linguist. Asking them to download and install 1 GB of Qt SDK is not acceptable for most of them.
Because this is a very specific but also very common use case, it would be nice to have a standalone and easy-to-use installer for Qt Linguist only. That would be the "Translator Kit".
The targets for this installer are mainly Windows and Mac OS since they are the most used (if not the only) platforms for non-technical translators.
More important, this is a security issue. Since the need does exist for real, there are alternative packaging and downloads for Qt Linguist from many third-party download sites. We have no guarantee that the included code is genuine and free of malware. However, non-technical translators are very much tempted to install them. Providing an official small "Translator Kit" from the Qt site would be safer for everyone.