Why would keeping a few reps in the tank be better than training to muscular failure for strength gains?

An increasingly common way to prescribe resistance exercise is to use a velocity loss threshold (VLT). The performance of resistance exercise according to a VLT means that once a certain percentage of velocity loss from the fastest repetition (typically the first) of a set is obtained, the set is terminated. For example, a VLT of 25% would mean that the individual stops performing repetitions once they complete a rep that has a velocity 25% slower than the fastest repetition. Consequently, a lower VLT typically means sets are completed further away from muscular failure than sets with a higher VLT. Evidence suggests that VLTs ≤ 25% are superior to greater VLTs for increasing strength.^[1][2] Why might that be the case? One hypothesis for the superior effects of lower VLTs is mitigating muscle damage.^[1]Training to muscular failure produces greater muscle damage and neuromuscular fatigue than ending sets a few reps shy of muscular failure.^[3][4][5] Muscle damage negatively affects the recruitment of high-threshold motor units and the ability of muscles to produce force,^[3] as well as motor skill learning.^[6] It also delays recovery from exercise, which can lead to a reduction in training frequency and less exposure to the exercise(s) on which the individual is interested in increasing strength. Therefore, training to muscular failure can compromise increases in muscle strength, particularly for complex movement patterns, by impairing training quality.^[1] By training with a lower VLT, an individual can lift heavy loads (≥ 80% of 1-repetition maximum—the most important factor for increasing strength) and practice the exercise of interest more often. Another hypothesis is that training with lower VLTs preserves maximum force-generating capacity through its effects on muscle fiber-type distribution.^[1] One 8-week study found that training with a 40% VLT produced a reduction in the proportion of type IIX muscle fibers (the fastest and most powerful muscle fiber type) compared to a 20% VLT.^[7] Because type II muscle fibers possess a higher force-generating capacity and generate force more rapidly than type I muscle fibers, training regimens that retain or increase the proportion of type II muscle fibers are theoretically superior for strength adaptations.