Reasons Russia and Putin could favour a candidate:
- policy wise it may help Russia
- personal wise it may help Russian oligarchs and their looting and laundering of wealth
- it may be because they see a candidate as someone who will weaken American institutions
- it may be because they see certain candidates as great vehicles to increase american partisanship and increase the divide
The reasons WHY Russia is doing it should not matter.
What matters is that it is acknowledged and that as much is done as possible to prevent and minimize it.
What Trump is doing is shameful. He is calling his own Intelligence Agencies Democratic propagandists for doing their job. He is getting rid of people in the agency doing their job. And he is making it more and more likely that anyone in intelligence who would bring this forward, just shuts up in the future.
Of course Trumpsters cheer this on the all way, showing once again, they have lost any ability to put country over Trump.