It's statements like that which drive me crazy. It may very well have lower overhead, but even a function call has overhead, and OSGi's overhead is not small (at least last time I used it, circa 2012).
Remember Eclipse? Remember how, once you installed a couple of java plugins, it'd take up to several minutes to start up? All those plugins were OSGi, via the Equinox framework. The overhead was noticeable and severe. Contrast that to IntelliJ, where I have it set up to support a dozen or so languages, all with various plugins, and startup never takes more than 30 seconds. Still not as fast as I'd like, but I shudder to think how Eclipse would manage.
I also echo a lot of the commenters here from the development perspective. OSGi is one of the least pleasant systems I've had to write for. Some of that comes down to Java's questionable approach to dynamic class loading, but OSGi added a ton of cruft and complexity on top of that.