Historically, "liberal" encompassed markets. I.e., historically, "liberalism" encompassed capitalism (in the sense of being mostly free to trade one's labor for others' goods and services). "Left-leaning" thinking is generally very suspicious of, if not outright opposed to, capitalism, and in that sense "left-leaning" is very illiberal. The meanings of these terms have shifted somewhat over time, so to equate "left-leaning" and "liberal" isn't wrong at all.
One distinction I find helps is between "capitalism" and "capitalist". To me "capitalism" == "freedom to trade property, labor, goods, and services" (which, due to human nature, does lead to wealth accumulation), while "capitalist" doesn't mean "someone who believes in capitalism" so much as "oligarch" / "robber baron".
A colleague once put it to me like so: trust in capitalism, not capitalists.
Capitalists all too often rent-seek, and because they have accumulated enough capital to have outsize political power, they are a threat to their societies.
Capitalism, in so far as it produces capitalists, is dangerous, but if the alternative is less freedom for individuals lest some of them become tomorrow's capitalists -especially if it is significantly less freedom- then I'd rather stick to capitalism. Of course, this is a result of my definition of "capitalism", and you might well disagree, but forget what word we should use to name a system with such freedoms. The important thing is the idea that those freedoms are a good thing, and that not having them is a bad thing, and that the price to pay for them is the risk of oligarchs arising, and that we need mechanisms to deal with that problem that don't throw the baby out with the bath water!