Up until a few years ago, when playing almost any variation from the Street Fighter series on a console system, there was a slight to severe bias against players who didn't play on stick.
They weren't considered "real players" because it was felt that pads didn't provide an arcade-like experience. Also, Evo rules (the standard for most tournaments in North America) state that you are allowed to use macro maps (e.g. map one button to 3 x K).
Both Xbox and PS3 controllers have eight buttons (not including L3. R3. Select or Start ). These controllers allow players access to all of the buttons that are on an arcade stick (I'm using arcade here to indicate six-buttons as most sticks produced now have eight), as well as have two other readily-accessible buttons which can be mapped to macros which register more than one button press when pressed.
When I competed at Evo 2009 in vanilla (note, I am in no way pro), I mained Sagat and used a PS3 pad. When I set up my button macros, I set up my L2 button to be a MP + MK. which allowed me to more easily execute Tiger Uppercut -> FADC -> F + HK -> Ultra:
At the time, the MadCatz TE sticks (thank you Mark Julio ) weren't as prevalent as they are today (the sticks were introduced when the Street Fighter series was rebooted with Street Fighter IV ). These sticks include an eight-button layout in Street Fighter four mapped the extra buttons to PPP and KKK by default.
Before then, sticks from Hori were pretty much the norm, and they only provided the standard six-button layout, so it was seen that pad players had the advantage because of the ability to (legally) assign macros to the extra buttons.
There are players who that claim that they actually have better responses on a stick due to being able to use multiple fingers to hit buttons (whereas on a pad, you typically use your thumb to hit multiple buttons, sliding it over them).
Most importantly, there are some fighting games which contained glitches at various points
which allowed input from the D-pad and the analog sticks at the same time. This allowed for things such as a walking Spinning Pile Driver from Zangief (although it is possible to do without dual directional controls). When these glitches were known, it was something that had to be watched out for in tournament play.
At ECT2, DMG Inthul took third in Super Street Fighter 4 using a PS3 pad (as well as the tournament MVP), earning him the nickname "pad-long". Note that in his bracket he had to beat Sanford "Santhrax" Kelly and Arturo "Sabin" Sanchez (not exactly newbies) to do this.
It was after this point that I feel that acceptance for pad players grew and you started to see the focus on more pad players to the point where you now see them in the top of the brackets at major tournaments. Shissa and Vangief made splashes at Evo 2010 while recently Wolfkrone (who plays a very technical character, C. Viper ) has been very visible at major fighting game tournaments lately (although it should be noted that he's played Street Fighter X Tekken from day one on stick).
To that end, I believe that the answer was always "no", that to play at the professional level (defining professional as consistently placing highly at majors), it's just only within the last few years that it's become more accepted as a matter of choice (although beware, Evo rules state that you can't use wireless controllers, so always bring the wire !).
It should also be noted that this mentality doesn't really exist in the Marvel community. For the longest time, Marvel vs. Capcom 2 (which kept the fighting game community on life support for more than a decade ) was played on consoles competitively on the Sega Dreamcast (due to it being the most faithful port of the game).
During that time, one of Marvel's most famous players, Fanatiq was involved in two of the biggest money matches ever, playing on pad. The first one being vs Toan with $50K total:
And the second as part of Team Cali against Sanford Kelly with $24K total: