For sure. Those oakum + lead joints were problem-free a century after they were installed. How many of us can expect that from the things we do at work?
The only reason some of that pipe needed to be replaced was that it was fused (by rust) to mid-20th-century galvanized pipe that had rusted completely shut.
Generally the lead joints described above were only used for waste plumbing where the max pressure is very very much lower than the water supply pressure
Those lead joints were leaching lead into the water. If it was a supply pipe, as opposed to a drain, then people were ingesting that lead. It needed to be replaced whether it was leaking or not.
The lead in those joints never touches liquid. It's a sealant on the back of the oakum, which is what does the actual water contacting.
Also, nearly all water supplies (municipal, at least) are pH adjusted to be slightly basic, which causes lead to form lead carbonates and oxides, which is (basically) insoluble in cold water. Still good policy to replace lead supply lines, but not a crisis unless you allow your water quality to fluctuate (ala Flint or a number of other US cities, sadly)
A big source of lead can be recently sweated copper lines (takes a while for the corrosion control to coat it), but lead solder isn’t supposed to be in potable use anymore. And old fixtures!
Yes I've found it's very frustrating looking for "genuinely zero lead" brass and bronze. Almost all scrap has lead in it to some degree, and even new metal often has a trace.
Neat, this dovetails with another interest of mine, pottery. NaF is "sodium feldspar" and Ca-Si compounds are "wollastonite" among others. Both useful as fluxes in metal casting, in addition to their pottery uses.
It was just the drain pipe system that was built that way (at least in the house I helped out with). All of the supply lines were galvanized steel, replaced with PEX.
The only reason some of that pipe needed to be replaced was that it was fused (by rust) to mid-20th-century galvanized pipe that had rusted completely shut.