Hello,
it make ppl look dull headed.. PPL on other tech knew almost all about the system they are wrking on..
No, it is because most mainframes are professionaly managed and supported. There is an infrastructure that has been successful in every business environment i have ever seen or heard of. It is not unlike a professional football team (US style). Everyone has their position to learn and perform. This is true of coaches, managers, support people, etc.
Most developers on "other technology" know nearly
nothing about the entire platform (especially Win-based systems). The MS goal was that they intended to be able to support those systems with "Users" rather than specialists. It should load out of the box and be immediately usable. And it is as long as the "stuff" is personal. The biggest failing of the MS environment is that the professional infrastructure is not there yet. Yes, some organizations have worked to implement a supportable environment, but many, many of the large attempts have failed.
One of the neat things about doing things on a Win-based system is that (if you have Admin priviledges) you can try almost anything you'd like to try. Not so on the mainframe (if it is at all well managed). If you take down "your" environment on the pc, not a big deal. If you find some way to take down a manframe, it gets Very Ugly.
Another big issue is the lack of standards on most Win-based systems. Good Standards, properly enforced are one of the biggest strengths of most mainframe environments. From what i see nearly everywhere "rolls their own" which makes hiring skilled Windows people problematic. So far there are few "industry standards" associated with the Windows environment.
There are many excellent offerings, but they don't all play well together. Some of the work i did over Y2K was to support the migration of several Mainframe applications to some purchased software. I was the Y2K remediation DBA for the mainframe and they needed someone to install and migrate the mainframe data to SQL Server. So i learned SQL Server. . . When we tried to run the purchased apps, they ran well individually. We found out quickly that a SQL Server DLL was needed (might have been sqlsrv32.dll

). Unfortunately, these products needed different versions/releases of the DLL (and of cource as there wold only be one, they all had the same name).
To build a solid environment from scratch takes a very long time and will need specialists in several areas. Some of these are security, database, source code management, storage management, production promotions, system and application backups, disaster recovery plans, and on and on and on. . .
If you chose to stay in IT, this will become more understandable.