Lol.
The community decides the language
Okay, and you've admitted Lemmy as a (global) community has decided this usage of this verbiage. Problem solved, by your own metrics, this is the common usage here. Great, stop complaining then.
Both the left & right in the US use liberals in regular contexts to refer to leftists who also refer to themselves that way. Telling an educated person in the US but liberals aren’t leftists/progressives is liable to elicit an incredulous look like they’re wondering if you’re stoned or just stupid.
I get that you assert this, but that doesn't make it true. Most people pick up on the distinction, just like being told other distinctions.
It’s often claimed here that leftism & liberalism are mutually exclusive: no one can be both
Am I claiming this? Further, we all know what comparing and contrasting is. Just because there are comparisons, does not negate the contrasts.
And people are a mix of policies, no one is some purely liberal, rightwing, socialist, etc person. Policies can be grouped into various political ideologies, and people generally describe themselves as such given whatever they vibe with the most.
Read The Rise and Fall of the Neoliberal Order - it literally addresses all of this and explains how capitalism has lead to "corporate monarchy"/"corporate fascism."