In other words no, a 5th generation fighter with internal weapon bays still possesses unique strike capabilities that a 4th generation fighter simply cannot match, especially if said 5th generation fighter has slightly larger weapons bays like F-35 and is able to carry a range of powered stand off weapons like JSM and AARGM-ER.
Agreed:
Another argument in favor of 5th Generation fighter aircraft is that In an air superiority role all Air to Air weapons (even the largest ones such as the PL-15) would fit in the weapons bay, and not compromise stealth by being required to be carried externally on hard points. In an air to air role especially with very long range air to air missiles a stealth fighter like the J-20 is invincible.
Ground attack role:
Not sure if the F-22 has an intended ground attack role as well but it is believed the ground attack role is reserved for the F-35.
When the first generation stealth planes were used like the F-117 Night Hawk these were not fighters in the true sense but strike aircraft. The small weapons bay limited their ability to carry out long range 400 km + stand off weapons strikes. The first use over Iraq was spectacularly successful but one F-117 was downed over Serbia.
Is a stealth fighter more vulnerable in ground attack mode when it has to come within detection range of ground radar which may be more powerful than airborne radar installed on adversary fighter jets?
There are unconfirmed reports of Israeli F-35s suffering damage from Syrian S-200 systems and crash-landing when returning from missions
over Syria. Israel explains these as "bird hits" .
China seems to following the US pattern by dedicating models of stealth fighters ( J-31, J-20) in specific roles instead of looking to an F-35 type multirole platform.
Interestingly the first likely combat debut of the J-20 is being
debated globally most notably in India. Defense analysts in India (either through ignorance or a deliberate misinformation attempt) are dismissive of J-20 capabilities as being a threat in the local theater ( specifically Ladakh and Tibet).
The argument goes that the J-20 is primarily intended to take out large targets such as tankers, AWAC abd EW aircraft, heavy transports, ships, or basically large targets. This is ideal for coastal defense over flat open ocean devastating an attacking naval force from a distance. In the Western Theater Command environment there are limitations on the J-20s capabilities. Taking on AESA equipped thrust vector capabilities, MAW and EW suite equipped 4++ aircraft (basically Rafale ) in a mountainous environment with radar clutter will be difficult. The Rafale's would be making use of the terrain. with tactics such as "nap of the earth " flying which makes it difficult for PL-15s to hold the radar lock and maneuver in a twisting turning dog fight. Additionally the J-20s maybe at risk from being detected by improved ground radar in a short range environment. A within visual range confrontation is of course impossible.A BVR engagement over a flat plateau (such as Tibet) would end badly for any 4th generation aircraft trying to take on the J-20.