It never held all that much. The 'progressive' movement used to support eugenics as far late as the 1960s in some places. And economic freedom used to be seen as a conservative value exclusively prior to the 1980s and 1990s, but today it has contributed to lifting billions of people out of poverty, and many on the "neo-liberal" left support it. More recently, the left is also slowly moving towards supporting a preference for skilled over unskilled immigration to protect vulnerable and marginalized citizens' jobs and reduce concerns over social frictions, something that used to only be a talking point for conservatives.

Economic freedom has always been a key Liberal value.

Protecting jobs has always been a key left value.

>The left is defined as moving. That's what "progressive" means

It's a little more complicated than that. Progressive and left can coincide in some cases, but they're not the same thing. Left ideas were often deemed "regressive", both in the economic and social domains.

In fact, according to Marx himself, capitalism (the essense of the "right" in European terms) is a revolutionary movement itself, which breaks down all established traditional order and social conventions.

And inversely, leftish causes, were often considered as anti-progress: the protection of workers from automation, environmental issues ("tree-huggers"), protesting against GMOs or nuclear power, celebrating native cultures, and of course protesting modernity and consumer society (a massive theme in the 60s and 70s leftist movements).

And of course in the 19th century, a huge number of leftist intellectuals were Romantics or close - against the rise of industry and alienation.

The reality is that the "progressivist" element, an inherently capitalistic dynamic (historically only partially shared with some parts of the left), has increasingly eaten up the folksy elements of the left, to the point that the modern left is mostly an upper middle class movement.