"C and C++ folks had been fine with that approximation for decades, but in the recent decade they had enough and started to provide an option to enable the link-time optimization (LTO)"
There has been a technique (the 'unity build') that approximates a poor-man's LTO for a long time. Basically you #include all your cpp files in to a giant translation unit and then compile it :)
VC++ first shipped it in Visual Studio .NET (early 2002), and I don't remember it being touted as the first production-quality implementation of the concept, so I assume it was around elsewhere before that.
I dunno about "much" older but I'm sure it was part of the Xbox tools in 2001... they provided some kind of early build of the VS2002 compiler. VS2002 proper was released in 2002 (oddly enough).
LTO is much older than this, even for C/C++
Just not in GCC :)