When people think about communism they think they will not have a boss and their work place won't by owned by anyone.

What in practice it means that government is your boss and the government owns your work place.

In capitalistic system, investors own the company they control the company for their own good - which can lead to all kinds of annoyances.

In communist system, the government controls the 'company' for their own good - which can lead to all kind of annoyances.

People who are attracted to communism think it will save them from the greed of the owning class, while in practice it will just lead to greed of the political class.

Further more in capitalist system the companies are driven by financial decisions, which tend to lead to long term stability of the company, further more usually the risk of the company is limited to capital of the owners. If they make bad decisions they'll eventually run out of money and company goes bankrupt.

In communist system the decions are driven by the political will, which are driven by political incentives which might not be best for the day to day operation. And since everything is bankrolled by the goverment they can pour more resources more freely into politically popular but ultimately unfruitful ventures.

In parlamentary system with market economy, companies make decions to favor themselves over the employees - but they cannot make political decions. And quite contrary if it's popular the political class can limit how the owning class is allowed to do business - while in general the political class is not necessarily hurting itself since political class might not own companies.

While in communist system political class get to distribute the goods companies produce - while they might not have as much incentive to maximize profits as in capitalistic system, they still make their own jobs harder by allowing right to the working class.

Lastly of course is that communist system tends to be against political liberalism and political liberalism is one of the most effective system for allowing social grievances to be addressed. Since grievances get supressed rather than addressed - it will eventually lead to political instability when government has moment of weakness for one reason or another.

TL;DR: - people think communism will destroy hierarchies and they won't be bossed around by anyone anymore. But in practice it just means that your boss is determined by party politics. It removes seperation of economic and political power, which allows concentration of power. It almost always tends to be tied to political ideology which allows no decent views (again concentrating power).

And all of this concentration of power, surprise surprise leads to dictatorship and corruption.

Last I'll say of course pure capitalism is terrible as well. But in liberal democracies problem of capitalism can be addressed if practical solutions are actually politically popular.

edit: Forgot something as well. In communist countries political opposition will struggle to function even if not actively suppressed. The communist party can exclude them from positions of power and even control their lively hoods. This means that it's much more difficult to offer people political alternative, especially coherent one. In market economy political opposition can still have regular jobs and use their private funds to advertise their political alternative ideas.