Surely anything you do with a GC you can do in a language with no GC?
The real disadvantage of a GC is that it makes schedule-based optimizations difficult-to-impossible, which are a major optimization class in modern systems code. Even if it performed identically to manual memory management (which it doesn’t), the loss of scheduling control would adversely impact performance of codes that make heavy use of scheduled-based optimizations e.g. modern database kernels.
There are also lock free algorithms written in Assembly, that doesn't mean the authors had any fun writing them.
Unfortunately Modern C++ is mostly found in conference talks.
Most the real life code looks quite Orthodox C++ to me, including from big name ISO members on their SDKs.
I would suggest that you might be projecting your experience on the rest of the industry. I’ve seen nothing but modern C++ at several companies for the last decade. I haven’t seen legacy C++ anywhere in a really long time, thankfully. I occasionally see very early C++11, which is definitionally modern though dated by modern standards. Baselines tend toward C++17 these days on average.
The magic is called productivity
that doesn't mean the authors had any fun
You went from implying that it can't be done, to saying a GC is about productivity, to saying it's about "fun". The goal posts are all over the place here.
Meanwhile, I've done it over and over in C++. The reality is that memory allocation shouldn't be a big part of a fast data structure anyway, let alone a good lock free algorithm, because if you're relying on allocation that much you are hopping around in memory, not to mention leaving a big part of your data structure to a black box.
Unfortunately Modern C++ is mostly found in conference talks. Most the real life code looks quite Orthodox C++ to me, including from big name ISO members on their SDKs.
I don't know what either of these is supposed to mean.
If you want to be explicit, tell me what algorithms need a garbage collector, because this all sounds a lot more like something you want to be true or want other people to agree with than something learned from extensive experience.