I'll admit that's a very optimistic view of things though. It has to be a little hard to stick your neck out in Russian politics when the result may be transdermal poison secretly smeared on the insides of your underwear. (And that is not an exaggeration or speculation of the risk)

Also there are investors, external and internal, which are too all over risks, this damages economy and national currency.

That's not what "Smart voting" is about. The SV works by recommending the candidates that a) are not the ones actively pushed by the Kremlin b) have a shot at winning or credibly pretending they did. These could be some batshit crazy Stalinists, mobsters or whatever - the point is that they aren't the guys that the suits in Kremlin have already secretly anointed.

In short, this will hurt Kremlin's credibility and put an organizational tax on all its future efforts. With the pandemic, an economy in deep crisis and Putin's term ending in 2024 he'd need a lot of political capital and SV hits him where it hurts.

Here's a bit longer explanation. The point is that in autocracies elections are not rigged by altering an Excel column. In Russia we have empirical statistical evidence to this: the presence of poll watchers has a very clear effect on the electoral outcomes, the rigging elasticity is capped by the anti-Putin sentiment etc. This is a consequence of how the elections are organized: the local authorities are handed the required numbers and told to deliver, as a test of their loyalty, capability and popularity. They have limited number of ways for this: they can mobilize their base, force their dependents (state employees, the military etc) to vote or press local polling committees to alter the results. If they overplay their hand, they will face local unrest (this actually happens a lot) and the Kremlin will jettison them without a second thought - so this is a balancing act. The efficiency of all their tools is capped by the popularity of Kremlin and the overtly pro-Kremlin forces, and it is at all-times low and still going down. So to get things done they need to depress the turnout - and this creates an opening for organized opposition. If openly pro-Kremlin candidates are hurt en mass then the president's admin would have to renegotiate with both the winners and the losers, effectively losing a lot of organizational cohesion, and that's on top on very public humiliation. With Putin's popularity near its all-time low and going down and 2 years before a very uncertain end to his current term, that's a lot of damage - although likely far from enough to topple the guy. But we take what we can get and this may be a rather large take.