One of the culprits, of course, is we tend to design and simulate with perfect components. Wires have zero resistance, capacitance, and inductance. Inductors and capacitance have no parasitic elements in our rosy design world. Even the values of components will vary from their ideal values and may change over time.
Because of that, [devttyS0] uses trimmer capacitors in the resonant part of the circuit. That way you can tune to account for circuit variances. That’s not the only practical advice offered. Need a small capacitor? Twist some wire together (a trick we’ve heard called a “gimmick capacitor”).