Yes, up to the architecture and OS limit. A 32 bit machine cannot use more than 4GB and a 32 bit OS on a 64 bit machine can't use any more either.
A machine bought years ago may have had enough memory for its time.But every time there is an operating system patch, it almost always demands more memory. The Internet has also put more loads on our RAM - web pages seldom used graphics when I started and even a few years ago most of it was low resolution (meaning low memory needs) and movies were unkown.
That's all changed. Web pages now have many memory hogging graphic elements.
Finally, for Windows OSes, virus control has become more and more difficult, requyiring ever larger and more complicated programs. Every time your virus scanner updates, it probably gets bigger and needs a little more ram.
Our habits and expectations have changed also. In olden days, we'd close one thing before starting another. Today I have at least half a dozen things going at once and if you count browser tabs (which eat up ram also), I have twenty or more always.