Changing your hosts file helps but it would only block hostnames primarily used for ads and trackers - it wouldn't address those trackers and ads loaded from hostnames shared with actual content. The more sophisticated sites will proxy their tracking and ads through their main app:

E.g. www.cnn.com/ads.js

I prefer having multiple layers just in case anything drops off:

1. VPN DNS / AdGuard local cached DNS 2. uBlock Origin

It's like wearing two condoms (but it feels better than natural).