I can see why newer employees get upset with the lack of support on things like 'career progression' and 'training materials' etc. The company has grown up very quickly and was much smaller a very short time ago.
The fact is, new hires / prospective recruits see a well established company that has a lofty reputation. With that comes the expectation of getting properly trained, having clear career path and properly established processes - as they should. While some teams have these now, others don't. Messaging to new hires is important.