Because the city was razed to the ground. Men, women, children. All decimated. If many Jews didn't flee beforehand no one would've survived the initial blood-lust. There's testimony that during the siege food was cut off and so some even resorted to eating their children.
It's not about the number of deaths, it's about the severity of it all (intensity and duration). If there were only 30,000 people in a town and that entire town was slaughtered: men, women and children alike...with no quarter, no rest or surrendering allowed...and then the town burned with every building that survived the burning smashed to powder, that's considered a massacre.
Secondly, we need to remember that Daniel (as well as the disciples listening the Messiah during the Olivet Discourse) had no concern about "the world". They cared about what was going to happen TO THEM. Their concern was for their people. The Angel and The Messiah were speaking about the great suffering that would befall the Jews that wouldn't be matched "since there was a nation".
What nation of people has suffered (in intensity and duration) for hundreds and hundreds and hundreds of years, since they were expelled from their homeland, more than the Jews?
We have to acknowledge (though some might not want to) that throughout history there were many surviving Jews hated and mistreated by many gentile Christians & Catholics for "murdering the Christ"; also considered "heretics" and "judaizers" to both papal authority as well as to laity and royalty...kicked out of countries...blamed for diseases...and they were also the primary victims of the inquisitions. And on and on throughout history.
So we have the example of Jerusalem 70 A.D. against Rome.
Do you think what Rome did was the first time doing so, or was it a [normal practice] of theirs?
Let's look at the Punic War:
The
Siege of Carthage was the main engagement of the
Third Punic War fought between
Carthage and
Rome. It consisted of the nearly-three-year
siege of the Carthaginian capital,
Carthage (a little north east of modern
Tunis). In 149 BC a large Roman army landed at
Utica in North Africa. The Carthaginians hoped to appease the Romans, but despite the Carthaginians surrendering all of their weapons, the Romans pressed on to
besiege the city of
Carthage.
^
Notice the last line:
The Carthaginians hoped to appease the Romans, but despite the Carthaginians surrendering all of their weapons, the Romans pressed on to
besiege the city of
Carthage.
^
They give Rome their weapons and Rome still destroys them unmercifully.
^
In the spring of 146 BC the Romans launched their final assault and over seven days systematically destroyed the city and killed its inhabitants.
LET'S EXAMINE ROMAN INFANTRY TACTICS:
Roman infantry tactics refers to the theoretical and historical deployment, formation, and then
they would use siege weapons and the soldiers to assault the city and burned the city to the ground to prevent its later occupation and use by the enemy.
So tell me, how is Jerusalem any different and more special for having Rome do to them what Rome did to EVERYONE ELSE?