That’s a Pl/Oly mindset rather than a BB/hypertrophy mindset. Totally valid advice in the right context.

Long story short, failed reps get much more risky and problematic as the weight you’re lifting approaches your 1RM.

It holds true, but with some caveats.

Generally training to failure is completely fine for say a set of tricep extensions. Generally safe.

However, training to failure on compound lifts like a deadlift or benchpress, or involving sensitive muscles like a shoulder press, isn't.

Technique generally suffers at the point of failure. Making a habit of doing thousands of repetitions in the next decade at the point where technique fails, on an exercise that can mess up your back permanently, or your shoulders, is bad advice.

For these exercises it's better to stop 2 reps short of failure. This is more safe. Also it requires moderate recovery getting you back in the gym quicker, meaning you can compound more incremental improvements in a given training period (say 5 years).

Even then, some still cautiously go to failure to keep an understanding of what their failure point really is. You could go for a PR once or twice a month for example and go to failure, with a proper warmup, spotter etc. But purely for hypertrophy there's not really a point, this is more for strength training.

Generally people that say they train to failure mean 2 reps in reserve. Training to absolute failure on all muscles is very rare and generally advised against.

not an expert, 2 years of serious lifting, but this is probably a good adage for the average person from my current understanding

training to failure puts you at higher risk of injury and there are diminishing returns as you approach your 1 rep max and/or failure

hypertrophy can happen with more reps or more weight

strength gains are usually just focused on progressive overload

though, of course, hypertrophy will happen either way and contributes to increased strength, but this seems to be further confirmation that you can gain muscle size either way

It's definitely way more nuanced than that. You have to approach exhaustion to get the body to eventually build strength. But you need to carefully time your rests/deloads and handle plateaus with more volume.

I’ve never heard that, it’s usually the opposite- people do strip sets and the like to reach failure

Failure also taxes your nervous system and joints which don’t take as kindly to stimulus as muscles do and take longer to recover (or accumulate damage in case of joints)