The mount is not the part that fails. What the fastener landed in is.
Wall-mounted televisions come down for one reason: the fasteners were never in anything that could hold the load. The bracket is almost never the failure point — brackets are rated well beyond what a modern television weighs.
Lag bolts into framing hold a television indefinitely. Standard framing is spaced predictably, which usually means the mount can be positioned to catch at least two studs, sometimes with a small compromise on exact centring.
There are legitimate answers — toggle anchors genuinely rated for the load, or a backer board spanning two studs with the mount fixed to that. What is not legitimate is plastic drywall anchors carrying a television, whatever the packaging claims.
A full-motion arm multiplies force considerably when extended, because the television's weight is acting at the end of a lever. A mount that holds fine flat against the wall can pull out when someone swings it to watch from the kitchen.
It is a common request and worth a caution: heat rising off a firebox can exceed what electronics are rated for, and the viewing angle is high enough to be uncomfortable over a long evening. Neither rules it out, but both are worth knowing first.
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