Don't get yourself worked up into a lather just yet.
You may not have been able to spot "Stranger Things," "Big Little Lies," or "The Handmaid's Tale," three of the biggest shows of the year--amongst the 2019 Emmy nominees, which were just announced. But it all has to do with airdate.
Generally, the majority of episodes of a show must air in primetime between June 1 of the previous year and May 31 of the current year, though shows are also eligible if episodes were made available to voters before June, and then aired in June. Variety has the full rundown of the Emmy organization's rules.
Three episodes of season two of "The Handmaid's Tale" aired in July and August of last year, so the show was eligible and nominated in 2019 for directing (for the episode "Holly"), writing (also for the episode "Holly"), and guest actor and actress. Bradley Whitford is nominated for his role as Commander Joseph Lawrence, and Cherry Jones as Holly, but the show was not eligible for a series nom, or lead actor or actress.
Meanwhile, season 3 of "The Handmaid's Tale" debuted June 5, "Big Little Lies" premiered its current season on June 9, and "Stranger Things" dropped all of season three on July 4, all after the May 31 cutoff date. Neither "Big Little Lies" nor "Stranger Things" aired in 2018, so it's going to be a hell of a fight in 2020. Imagine, Meryl Streep vs. Winona Ryder. Reese Witherspoon vs. Millie Bobby Brown. Dacre Montgomery vs. Adam Scott. Elisabeth Moss vs. Nicole Kidman vs. Natalia Dyer.