Artillery changes the game paradigm.
It becomes about forcing your your opponent to attack you or lose their base slowly. So you always need have a position stronger than your opponent's depite having invested 700 metal arti. This is not difficult to do given the extensive defensive advantages.
You opponent can also snipe it so you need to dilute you army strength in order to prevent this.
They can also set up their position in such a way as to negate your artillery. Radar blocking and shields, as well as caretaker spam can negate a fair amount of damage, but as far as I can tell will not stop most forms of artillery. Spamming nano frames too!
The final option for them is to get more artillery than you, or to use theirs more effectively.
The pillager and tremor are sort of weaker than other arti in a sense, since they are always competing with reaper. There are plenty of times that the artillery wins out though. A single terra wall stops any number of reaper, and some maps sort of encourage a forward porcing style to park your arti in.