I think this is because bitcoin integrates with almost all altcoins, so that when the price of bitcoin goes down or goes up, it will also greatly affect the movement of altcoin prices significantly, but it does not rule out the possibility that bitcoin prices can be controlled by people in power.
Traders carry out trading activities based on the conditions that exist in Bitcoin. That's why there seems to be an alignment with altcoin prices. Still remember this?
- BTC UP -> Altcoins Down
- BTC Down -> Altcoin Down
- BTC Stable/Sideway -> Altcoins UP
Why is that?
When BTC UP, altcoins go down because most of them will do trading activities on BTC and choose to sell their altcoins to making another entry to the BTC to get a profit. That's why altcoins started to show a decline.
On the other hand, when BTC is down, why aren't altcoins going up? because there will be concerns from traders, if they hold their altcoins, they are afraid that BTC will go deeper, so they are start taking stop limit actions, and start waiting for the correction process to finish then entry. If there is FUD circulating, they will wait for the FUD moment to end.
When BTC goes sideways, traders start to feel that BTC is in good condition, there is no FUD, so traders start looking for alternatives to get profits, starting to actively trade on altcoins again and making altcoin price going up.
This is an example of normal situations on market. So, this is not a kind of control but is the alertness of traders who understand the potential and risks in trade.
IMO