The other function calls described in the linked answer give a synopsis of what needs to happen; the actual implementation details in the GNU C library are different, either using “constructors” (_dl_start_user), or explicitly in __libc_start_main. __libc_start_main also takes care of calling the user’s main, which is why you don’t see it called in your disassembly — but its address is passed along (see the lea just the callq). __libc_start_main also takes care of the program exit, and never returns; that’s the reason for the hlt just after the callq, which will crash the program if the function returns.

The library needs quite a lot of setup nowadays:

etc. See the x86-64-specific sysdeps/x86_64/start.S and the generic csu/libc-start.c, csu/init-first.c, and misc/init-misc.c among others.