France is something that could hopefully be well represented by the new coalition mechanic. They were very scary at the time and desired to push out their borders into what's now Belgium and Germany; it took multiple alliances to stall them. France and Austria also desired to push into Italy, it took the opposing efforts from one another to (largely) stall them.
Spain blobbed successfully for a large portion of the game. Holding Portugal, portions of Italy, the Spanish Netherlands, parts of Burgundy all for a substantial period of time. However due to a several factors began a period of terminal decline, and these were slowly shaven off.
Austria blobbed very successfully, and held a huge swath of territory at the end game date. So did Russia and the Ottoman Empire.
Blobs can and did happen in real life. The two issues EU has had with them is without player intervention they tend to never decline, and they typically went unchallenged while forming.
It's not so much that France and others attempting these things is unrealistic. What's unrealistic is the AI kinda going "aww, shucks" as the French march into Berlin, or how large Empires tend to not struggle to sustain themselves.