Different Gothic tribes cannot be conflated. Also important to note is that the 'Romanized' Goths only became so because they devastated, conquered and kept Roman territory - they weren't friendly settlers, they were neighbors the Romans had to learn how to deal with and use against other enemies.
> And the famine and pestilence were also becoming a major issue around the same time.
Not until later, and then in part because of Gothic devastation. If the Roman Empire had not been able to feed a few ten thousand armed people, it would have fallen nearly immediately, since that would have meant it would have been unable to field any significant armies.
> Modern historians realize a million people suddenly showing up would leave a massive archaeological record that isn't there.
It is.
Further, it's very hard to explain why it'd be hard to census only 90k people, an activity performed regularly.
The Crisis of the Third Century is what lead to the weakened state unable to cope with the Goths. Outside invasions were part of the problem, the Plague of Cyprian was a much larger part. The breakdown that occurred during this period led to widespread problems, they trade routes were damaged making it difficult to suddenly feed an unexpected influx of people.
>Further, it's very hard to explain why it'd be hard to census only 90k people, an activity performed regularly.
First, there wasn't a ton of time between their arrival and their revolt to count them. Second, the census had suffers a long period of decay by that point. Third, counting nomads is no easy work, and the general strategy of assessing taxes based on property didn't apply yet.
The Goths were a major part of the Roman army for a century before the uprising discussed, and the famine and pestilence were also becoming a major issue around the same time. And the Goths were no more barbarian than much of Caesar's army, their hostility came from the overall problems the empire faced.
>If they had numbered only a few ten thousand, the Roman logistics system would not have struggled so much to keep them fed, nor would it have been a major problem to account for them all.
The empire was struggling to feed itself, even a relatively small number of people in one area can cause problems. And the contemporary sources are dismissed because we know the things written down are propaganda based largely on guesswork. Modern historians realize a million people suddenly showing up would leave a massive archaeological record that isn't there.