Target selector stops parsing its arguments if an entry is not <argument>=<value>

Put or summon at least two armor stands

/say @e[type=armor_stand,argument=anyvalue,c=1] (where "anyvalue" can be even "") will find 1 armor stand (invalid argument was ignored, which is MC-101249)

/say @e[type=armor_stand,=anyvalue,c=1] (no argument)
/say @e[type=armor_stand,anyvalue=anyvalue=anyvalue,c=1] (multiple equals signs)
/say @e[type=armor_stand,anyvalue,c=1] (no equals signs)
These commands will find all armor stands - this means that everything after an invalid entry was ignored