Liberalism: a political and social philosophy that promotes individual rights, civil liberties, democracy, and free enterprise.
I think you are conflating the free enterprise to mean endorsement of late stage capitalism instead of a system of actual market competition. Please don't base this on the complete market capture demonstrated in the US currently. If anything the US is more like an authoritarian oligarchy with the illusion of democracy peddled through conflicting culture wars in the media. While there are great ideologies in play in something like socialism the reality is unless you could end the idea of money tomorrow their will always be inducements and incentives to hoard and leverage outsized resources outside of which ever community produced them in the first place. It's why US resource capture on smaller nations works effectively, and it's why Russian oligarchs have most of their wealth outside of Russia, etc.
Marxists are materialists. This is in contrast with the idealism of Liberals. While Liberals believe ideas are the force which drives change in the material world, Marxists understand that ideas are just a reflection of the material conditions they emerge from.
Liberal vs Marxist has nothing to do with being a materialist or idealist, and trying to conflate them like they are is very disingenuous and misleading. Not to mention that is not what a materialist even is. A materialist is someone who values possessions for comfort, think a hyper consumer, where as an idealist is routed in ideals, like equality for all, regardless of the difficulties in trying to accomplish such a task. If anything by your definitions a Marxist would be an idealist fueled by an ideal (communism) , and a liberal would be someone on either side as they value personal freedoms and ones ability to choose either ideology.
Either you are trying to be intentionally misleading or you need to take a step back from your own propaganda as you are parroting off information that is completely ill informed at best or intentionally misleading at worst. There are definitely issues in US institutions, but a liberal is not going to defend the shortcomings, they would be proposing ranked choice voting, imposing age limits, redefining our checks and balances, and making sure these systems are inherently democratic. We don't even have a true left in the US, we have a moderate center and then people like Bernie who are just barely into the left political territory in the global scale of things. A conservative would be someone who values conserving existing systems and institutions or leaving them as initially intended as they aim to conserve status quo. Seriously take a step back my friend, seems like you have been lost in an echo chamber for a while.
Damn now that's actually a great reason, at first I thought it would be a complete waste to stop people and yeah it probably is but at least it puts more cost on those companies participating in production and distribution so that's a win in my books.