I would agree, and I think most reasonable people would agree, that it's too early to attribute any economic news, good or bad, to Trump's policies. The same principle applies at the beginning of every new administration--it takes at least a year for new policies to work themselves into the economy and have an effect. There could be some exceptions (for example, if a President ever fired all federal workers on the first day, we would rightly attribute the ensuing rise in unemployment to that act), but generally speaking, this is a good rule of thumb. For now, Obama and the previous two Congresses own all the economic news, good and bad. That becomes less and less the case as time wears on, and after roughly a year, Trump and the current congress own the economy, good and bad.
The point I was making is that some Trump supporters were cheering positive economic news from even before Trump was sworn into office as his doing. That's a pretty crazy view--there's been generally positive economic news for quite a while. But if that's the principle by which hard-core Trump supporters want to proceed, then they have to do so fairly, and own all the economic news, good and bad. I would agree it's a nonsense argument--but it's based on the same logic as the argument of the Trump supporters making claims that positive news is due to Trump's policies (or simply the superlative radiance of his being in office). If it's nonsense to blame the bad news on Trump, it must be nonsense to credit Trump with the good news as well.
Now, if you're saying there are partisan leftists who are so biased as to want to present this kind of argument in a positive light (see! Trump is wrecking the economy!), then I agree with you. There are such people on my side of the fence, and they're dumb-asses. I would not claim that all liberals are reasonable and all conservatives stupid. There are reasonable, intelligent people on both sides, and I maintain hope, despite present appearances, that perhaps those people will learn to talk to each other and we can come together as a nation.