Tactical voting is a problem with any first-past-the-post voting system. It’s not a problem with leftists or liberals, it’s math. Our voting system mathematically encourages power to concentrate in two groups, forcing most people to vote against the person they don’t want more often than they have the opportunity to vote for someone they do want. Voters tend to understandably disengage and over time this naturally creates resentment among the least-represented which in turn inspires populist movements.
Here’s a video that explains voting systems in an accessible way:
While populist movements are attempting to correct misrepresentation, and often ultimately succeed at helping the system rebalance itself, they often become problematically fanatical in the process (and sometimes, in the case of Trump, fascistic). I personally don’t think anyone should be surprised by this; the longer people go without feeling heard, the more intense they feel the necessity to force their message across. I think the groups in power start to get lulled into a sense of security though when they’ve had what feels like stable political power for several decades. And given the way money and power intersect, these power centers are almost by definition going to become elitist and therefore increasingly out of touch with the populace over time.
This is a very interesting election; the elites on the right experienced a populist coup, and on the left we have this attempt to acknowledge and incorporate Sander’s ideas into the platform, which might work for a while although it remains to be seen if it will be thorough enough to succeed in satisfying the disaffected. But given how distasteful Trump is it may be everyone on the left will suck it up this time around and work out our internal differences when it’s safer to do so. As for what will become of the Republican party…that’s anyone’s guess at this point. It doesn’t seem like you could build a modern party on racism and xenophobia, but this rise of neo-fascist far-right parties is a worldwide phenomenon among Western countries at the moment. We shall see.