Why the sudden push to sell publishing rights now?

"Over more than 40 years I've never had anyone say to me, 'I sure am glad I sold my publishing when I did. It was the best thing I ever did'. But I couldn't begin to estimate the number of times that folks like Tom Petty, Paul McCartney, Steve Lukather, Tom Johnston, Roger McGuinn, George Harrison and Donald Fagen have told me that selling their songwriting catalogs was one of the biggest mistakes they ever made" - Randall Wixen of the Wixen Music Publishing wrote in Billboard about a recent surge of sales/purchases of publishing rights by Hipgnosis, Universal etc. So, why are they selling? - "writers' representatives have seen the money they make plummet over the past few years (especially if COVID-19 or an artists' age interrupted touring plans) and hope to make some nice fees for 'helping' them sell their songs. A lot of the encouragement to sell (and make money off of the sale) begins with the assertion to songwriters that 'folks are offering insane amounts for catalogs' and 'you should sell ASAP because Biden might raise the capital gains tax'".