For a beginner he will be learning wrong concepts like conio.h and clrscr must be used in all c programs
Return type of main is int but turbo c forces void
Difficulty in coding- turbo c forces all declarations before any function call while Standard c compilers allows declaration anywhere.
int a [10][1000] is not possible in Turbo C while modern compilers allow at least 100 times this size.
Far, huge pointers- another not needed concepts
C is for system programming, turbo c won't teach you any system as DOS is no longer in use.
"I code in Turbo C" is enough to get the exit ticket from any good company interview.
A C compiler is supposed to translate a C code to machine code. But the code generated by Turbo C is not for any current machines. It is meant only for DOS (just because DOS emulator is there it works in Windows, but not useful for making any application outside DOS)