Far be it from me to tell you what they were thinking back then, like I know, but I’ll tell you anyway.
The Mediterranean Sea was a “Roman” lake. But it took weeks, or months even, to get from the edges to Rome. The point of the Imperium was that it (Rome) was going to act as one thing.
On the eastern side of their Empire were the Persians, another giant political enemy, constructed as a normal absolute monarchy. On all the other borders were tribes of various kinds, nomads or farmers mostly. So geopolitical life in Rome was a constant grind of external military threats to be dealt with.
The Romans also had the Senate, with which the emperor was supposed to consult when he was developing his goals. The participation of people other than the monarch was built into their system. There were laws that, theoretically, even the emperor had to obey. That was different from Persia where no one could safely say to the king: “You can’t do that.”
The problem was that the Roman Empire was so big that it could take weeks or months for news to get to the capital, where lived the people who were supposed to decide what to do about it. A tribe had a food problem, or a visionary charismatic conqueror type popped up in a city, or there was an ethnic rebellion in the Holy Land. It could be the next year, or the year after before whatever they decided to do
