The analog temp gauge is used as a guide for temp trends. If grilling burgers, or steaks, etc., not so interested in spot on accurate numbers.
If doing a long cook, or smoking, then good temp readings are essential.
I have the Thermoworks Smoke, with dual readings for cooking chamber and the meat. It is spot on accurate.
The Tel-Tru is fairly accurate over time, but is slow to respond to temp changes.