Stagnation only happens in a market economy where they are forced to increase in size non-stop to stay stable. Trading is not capitalism, you can trade in market socialism and mutualism. Capitalism requires businesses, those require profit. The rich and everyone naturally want more money and power. Combined with new people and new jobs the economy is forced to grow or it can not provide for everyone, even if the population goes down. If no new opportunities for jobs for the young they make no money and make no resources. When that happens the economy declines and less have jobs. Those that have jobs must compete harder for them, meaning they will get paid less as the laws of supply and demand indicate.  No more money going into the economy means the economy grinds to a halt. It relies on new jobs opening up for the upcoming generations.

In communism people would innovate because that is what they want to do. Most people who innovate (all the scientists at NASA for example) don't get a major personal benefit, they do it because they like doing it. Because more people would have the opportunity there could easily be more innovation.

For your laptop only private property is seized, it does not matter if it could be used for work. It is personal property. However, what each person does is up to him/her. Justification is based on the situation and the people, I usually would not condone it but if it could save lives...... It is all dependant on society either way though.