@Henry *********
A tourist visa can always help to some extent, as it gives a slightly higher level of confidence for entry, but it does not guarantee entry. It can, however, make things smoother when you start approaching the upper end of what is normally accepted. In your case, two visa exempt stays without extension (around 119 days total) combined with a long stay outside Thailand would very likely also have allowed another visa exempt entry. Beyond that point, though, it would have become pure gambling without a visa, which is why an METV would have been the best solution from the outset, and essentially what the IO was trying to convey.