What Retro Grouch is describing is that as the front derailleur pushes the chain to the right to go up from the 28 to the 36 the chain is coming in to the 28 at an angle. If all goes well, teeth from the 36 encounter the chain, hook it, and your chain is transferred over to the 36. With some front derailleurs it's possible that the chain encounters a tooth from the 50 first and up you go into high gear instead of the desired middle gear. This is more likely to happen when the small to middle ring tooth difference is small compared to the middle to large ring tooth difference. In your case 28-36-50 means 8 versus 14 which certainly has the potential for this problem.

Having the gaps reversed, large jump from small to middle and small jump from middle to large, does not have this problem and is used by the once popular half-step plus granny setup.