Question

英语疑惑 深深的疑惑ome researchers have come up with the finding that

Answer 1

实际上这个复杂的句子是这样的：

Some researchers have come up with the finding that influentials have far less impact on social epidemics than (it) is generally supposed.

就你的提问,如果原句里（即无 it 的 ） 除掉了 is ,句子的意思还是一样的,这不是说 is 是多余,而是说在无 is 的情况下, is 变成了隐含的单词.

至于你的第二个提问：我们可以推定 (it) is generally supposed 的后面是 to be the case .

而 the case 是指 “having an impact” .