The advice against using pure black is reasonable and sound for areas of colour and for art that is trying to match how things appear in nature; but I don’t believe it was ever correct to apply it to simple text when your goal is reading rather than art.
The original article here doesn’t even not use pure black, it uses a quite saturated dark blue for its text, which I find quite obnoxious. I find fully desaturating its #113654 to #303030 improves things markedly, and darkening it to #000 makes it even better.
Mind you, I’ve recently shifted to using mildly-off-black (no lighter than #222, which is I think about the lightest you should go) for normal text and true black for bold text and titles (currently demonstrated on my personal website). I think this works pretty well.
The original article here doesn’t even not use pure black, it uses a quite saturated dark blue for its text, which I find quite obnoxious. I find fully desaturating its #113654 to #303030 improves things markedly, and darkening it to #000 makes it even better.
Mind you, I’ve recently shifted to using mildly-off-black (no lighter than #222, which is I think about the lightest you should go) for normal text and true black for bold text and titles (currently demonstrated on my personal website). I think this works pretty well.