Seriously? Because 2019 is not over yet. And the financial institution that will issue it needs time to issue it. It is the norm for W-2's and most 1099's to be issued by the end of January and sometimes early February.
For one thing, the IRS has not yet issued the 2019 1099-R form yet. Once the IRS issues the form then the IRS must write the electronic filing specifications for that form and get that to the e-file companies (like TurboTax), then TurboTax must submit their e-form back to the IRS for approval before TurboTax can release the form. That usually takes 3-4 weeks after the IRS first publishes the form.
Another considerations is Congress still had until the end of the year to make changes in the tax law which can delay things a month or two depending if forms need to be reissued.