Including reinvested dividends, European stocks have returned around 4% per annum since 1999, in dollar terms. Lagging the return on US stocks over the same period certainly but hardly "dire".
But only in dollars and only because the euro was at its lowest level ever against the dollar after its launch reaching a low of 0.9 euros to the dollar in 2000, it'd now at 1.1 dollars to the euro , surely the performance of the euro stoxx 600 should be expressed in euros not dollars. In any case we live in Europe not the US so why the fixation on the performance of the S and P 500. All the dividends have done is compensated for the loss due to inflation, in absolute terms you are just about getting back the money you invested in 1999 if you stayed invested through all the turmoil of the last 2 decades and the financial crash.