I want to set up a scoreboard for my server that tracks the amount of blocks that players use, and I was wondering if there was a way where you could get the command, in a command block or what have you, to accept all blocks used as a single criteria, or what I would have to do. Version is 1.14.2. Thanks.
This is just currently not possible for every item in the game. Consider suggesting it in the Minecraft suggestions reddit. The only work around would be to create a separate score for every block in the game, and have them all be added together. This would be completely impractical and the amount of commands would stress the game (although scoreboards have been heavily improvised in 1.14 / 1.13). If you are running a spigot, bukkit, or paper server, you could try searching for plugins that can do this, such as this one.