Abused to an extent, indeed, but I suspect part of the proliferation is due to the changing nature of the economy, when back in the day there was more of a binary between bosses and businesses on the one hand, and workers on the other.
So there weren't so many self-employed tradesmen, for example.
By the same token, 50 years ago I think employee status was more widespread in the trade? To the extent that that's largely disappeared then maybe that's evidence of the whole thing being abused.
But, of course, in the more modern era technology has facilitated self-employment, and the gig economy, for good or ill.
For example, even if the drivers here in NE Fife had been treated as employees in the late-90s (they weren't), the mobile phone explosion meant they became less dependent on offices with a telephone manned* 24/7, and they could thus become more genuinely self-employed with their own number etc.
In fact the explosion in self-employment can probably be traced back to Thatcher and Essex Man sort of stuff, but no point going into all that here.
*sexist language alert. I think words like that are generally frowned upon these days, if not specifically banned
