I also think that no amount limit is here in trading, but always better to start trading with a small amount, because in this way, we can get experience and knowledge, and i am agree with you that later on with the passing of time, we should grow our capital in trading.
By any possible means, a newbie trader must grow while building trading experience despite losses and regrets since that is really part of doing trades.
Starting a small amount is really a good practice so that newbie can have some glimpse on how actual trades work. And yes, as time passes by they must increase their trading funds since more funds on action = more profits.