Crossovers are as critical as any component in the speaker. Sometimes the most critical, but that depends. They have to be designed specifically for the drivers being used, to optimize what they do well, and to minimize what they don’t do well. They also have in consider and compensate for contributions of the cabinet and driver layout. The crossover points, slopes, and any compensation networks all have an impact. Calculations and computer simulations provide a place to start, but crossovers also need to be fine tuned to sound right, and that usually requires some subjective adjustments...some are better at it than others. Even the system and room that the speakers are in during the design phase has an impact...potentially a significant impact.
Regardless of the circuit, the parts quality matters too. All those little things that some claim can’t be heard all add up little by little. Many, many companies use components chosen by the accountants at the bidding of the board of directors/shareholders to increase profits. Others use the very best components they can find. Many sand cast resistors and cheap caps have steel in the leads. Many resistors have a notable amount of inductance due to the way their wound. Air core inductors are certainly a step ahead of iron core, and litz wire or foil are arguably a step above standard air core. Wire, connectors, physical layout all matter at some level. Do capacitors matter? 🤣
How far is the designer of a speaker willing to go with the crossover, and how many minor adjustments are they willing to make? At what point do they said "good nuff" vs peeling back another layer? It takes longer to make and evaluate changes....not all designers have as much time as they’d like with a crossover. All are factors in the end result. Yep...crossovers matter, and can be radically different from one speaker to the next.