I mean, a non-zero amount of people are effectively arguing against those new races and would scrap interesting and popular options like Dragonborn or tieflings for "Let's just mash together two of the existing races"
Also, the only options that 5E had that didn't exist in older editions were the Grungs, Autognomes, Plasmoids, and the MTG specifics (Loxodon, Simic Hybrid, Vedalken and Leonin, plus the semi-official planeshift batch). Everything else was playable in another edition
There's not infinite room for races in the PHB and half-elves can show up later in, say, a setting that actually uses them well like Eberron. If you simply must have them in the PHB, what do half-elves bring to the table that's more unique than what orcs, gnomes, halflings, dragonborn, goliaths, tieflings, aasimar, elves or dwarves bring to the table? Because frankly, I argue half elves being half elves kind of is exactly why they were on the chopping block, and half orcs were always just a poor man's playable orcs to begin with