I accumulated a DGI portfolio from 2010 to 2013, now I'm struggling with it. Here's the downside to doing it:
I've invested mostly in a taxable account because I've maxed out my deferred options. I have some nice holdings that were awesome companies 4-5 years ago, but are now struggling this year. One company can come in and displace the other, and you still win by owning the index because you get the net effect of economic growth.
One of my holdings is Genuine Parts Company - It is (was) the conservatively run parent company of NAPA with all these other parts divisions. NAPA was built on having a great logistics network and servicing the auto professional market (your corner mechanic), they got paid a premium price because of their ability to deliver on time. I have some shares in the 40s for its cost basis and its a nice dividend aristocrat.
CEO/CFO retire and new folks are promoted. They spent a bunch of money on acquisitions instead of internal infrastructure and are now getting taken to the woodshed by Amazon and Starboard Value has taken a big stake in their rival Advance Auto Parts. Its performance is now dreadful relative to the market, but I'm sitting on individual shares I have to pay pretty hefty capital gains on. Will they survive? Probably.
Banks were also on the aristocrat list until 2008. It was disproportionately full of banks and banks should be a reflection of the US Economy, with them going a little more up when times are good and a little more down when times are bad during leverage. BBT was a dividend aristocrat. "Paid a dividend through the great depression", 30x straight years of dividend increases, mainly located in the Southeast where economic growth is great. So in September of 2003, you pay $38/share for BB&T stock and get a $0.32/share dividend. 14 years later, FOURTEEN YEARS, it now trades around $46/share and your dividend is $0.33. It was trading below $40 a share before the start of this year! In the same time period, VTI went from $49/share to $127/share and paid similar dividends for the second half of the comparison period. The regulatory environment changed, scale began to matter more, acquisitions stopped being net positive.
There's also the investment theory that a company only generates a dividend when they can no longer meet an acceptable rate of return by expanding their own company. This would imply you're already buying "Yesterday's news" by going after the typical dividend aristocrats. Look at the components of the 1970's Dow Jones Industrial Average. How many of them are still in there today? The top 30 companies in the DJIA look a lot like the dividend aristocrat list.
https://en.wikipedia.org/wiki/Historical_components_of_the_Dow_Jones_Industrial_AverageTake it from me, I've been there, I've worked my rear end off analyzing, analyzing, analyzing, and my returns are within 1% of the index. It would have been a better use of all that time going on Rover and walking people's dogs and indexing the extra money.
Good luck in your journey, I wish I could get the last 10-15 years of time back I spent analyzing all this crap.