Dyson Sphere under construction?

[Anomalocaris]

The rarity can be accounted for if the process which causes the irregular dimming lasts only a short time in the life of any star that undogoes a similar process.  

The distinegrating planet hypothesis I advanced accounts for the rarity because if the planetary disintegration process periodically creates dust/vapors outburst large enough to obscure sizable portion of the star's disk, then the mass loss from the planet must be rapid and the planet would be  consumed in relatively short time.

If it takes a thousand years to consume the planet, and the typical star that ever had a large planet distingrate near the Roche limit lives for 10 billion years, then only 1 in 5 million stars which has ever had this process would be undergoing this process when we happen to be looking at it.

Yes, for "any star that undogoes a similar process." 

But how many stars do that? Important question. If many, then this is just an event like many others. If none, then we have an interesting event going on. But even then we don't know if it's natural or artificial.

My guess is this process is quite common.

One surprising thing that came out of the survey of all the planetary systems we discovered is in a large percentage of them, there is one or more large, Neptune to Jupiter sized planets orbiting extremely close to the parent star, with orbital period of just a few days. Since these planets almost certainly couldn't form there, it appears there is a some common process that robs some or all of the planets formed in outer reaches of a planetary system of their orbital energy and cause them to spiral in towards the parent star during early days of the planetary system's life. There is no known process that would stop a planet from spiraling all the way to,the Roche limit and distingrate. Indeed many stars' absorption spectrum seems enriched in heavy elements that should not be there in a prestine star's atmosphere, and probably came from consuming the debris of planets which spiraled all the way to the Roche Limit.

So this suggest to me a substantial percentage of all stars that has ever harbors a planetary system has pulled one or more planets in very close until the victim planets were destroyed. In this system we happen to catch the process of destruction in the act.